It's been ages since I last wrote a post in this blog and actually I never really looked for it to be popular or having loads of readers. I guess I started writing online just to something different from working on my PhD, which I finished two years ago (and you may read the thesis here), and to have a place where I may rant about things I like or I dislike... whatevs.
Well, now I inscribed myself to a new course on internet stuff... to be more specific, I am now taking an online course to get an MSc in Computer Sciences and Telecommunications. I don't really know how it is going to work because it's been only two weeks since it started but they assigned me two write two blog posts.
Well, I have decided to write just one addressing the two issues #rebel.
First, arguing about working on the cloud. This is clearly the way to go. I always like making fun of my girlfriend whenever she physically go to the bank to pay something. I think not working on the cloud is the equivalent of physically going to the bank, it's ok if you're living in the 90's but not anymore. Let me tell how it worked when I graduated from uni in 2005 (12 years ago!): I went to work, coded a long VBA script to run some actuarial simulations, waited for three hours while they were running and then... CRASH! Lights went off and all my work lost. This happened on several occasions.
This has not happened again to me since I started working on my PhD thesis. I realised, that compiling $\LaTeX$ saved my files automatically and that having it in Dropbox helped two purposes: Not only I could send the link to my supervisors and they would be able to read it on the spot, immediately after I had written it, and modify it if necessary. But also, I didn't have to worry if for some reason I lost my laptop or it was stolen or whatever, I could go to any other computer and my information was intact. The important stuff was safe.
I have a friend whose laptop was stolen from a train in Italy while she was on vacation just before coming back to hand in her thesis. She had no backup and was not working on the cloud. Result: she had to stay one more year to replicate anything. That is a problem of the past now.
I am now the Analytics director at a market research industry and I basically have two main tasks: run the models we create, which need a lot of data as input and take a lot of time to run. Hence I need some serious computer power to work and that makes my laptop a very heavy machine. THe other task is to go with clients and explain to them the insights we found from those models. Carrying my computer was a literal pain in the back, so I decided to buy this tablet/laptop which is very light, and I may carry it around and show the power point presentations I did in the other computer with no problem. Since in the office we use OneDrive from Microsoft, everything I do everywhere it's always there, as if had been always there.
One more thing on cloud-based working, if you're coding, use GitHub. Controlling different versions of a script and collaboration is very easy with these new technologies.
I think that the main message I want to convey is the following: go cloud now and welcome yourself to the year 2017. Otherwise, you're doing it wrong.
The second issue is about Wikis, but seriously... who doesn't use Wikipedia nowadays for everything?
In case you don't know already, the collaborative tool to know stuff about coding is Stack Overflow, give it a go.
Sunday, 12 November 2017
Sunday, 9 November 2014
Dividing by zero.
DO NOT DIVIDE BY ZERO!
Unless you're Chuck Norris, you should never divide by zero... just because you can't.
This is something one learns as soon as one learns to divide, I'm not sure when that is but I'm pretty sure is before turning 10 years old.
When one turns 20 and decided to study mathematics and has to deal with an analysis class one should be very aware of this fact, however I always say this at the beginning of the term... just to be sure that no one is going to write a division by 0. If such a thing ever happens...
I mention this because I'm currently helping a lecturer to grade his first year Chemical Engineering students and my brain is about to explode when they just casually divide by 0 when faced to a problem of the sort $\lim_{x\to0}\frac{\cos(x)-1}{2x^2}$.
I understand that if one attempts to evaluate directly with $x=0$ one simply can't since the function is not defined at that point and hence we asked only for the limit. My analysis lecturer when I was an undergrad has never been a huge fan of L'Hôpital's rule so I inherited this way of thinking and therefore my first instinct is to multiply the numerator and denominator by $\cos(x)+1$ and find a solution free of L'Hôpital's rule.
Nevertheless, engineers are happy with applying it and that's fine. The problem was that after applying it they now encounter the new problem $\lim_{x\to0}\frac{-\sin(x)}{4x}$ at which point they write again gives 0 over 0... which freaks me out again... and decide that it should be 0, thing that makes me believe they didn't get the idea of L'Hôpital's rule in the first place.
Of course some of the students handed in a decent homework and that is what one is supposed to do. But as one continues to see students writing divisions by 0 something is being done wrong. So here's the summary that encompasses everything one needs to know when found in a situation like this:
NEVER DIVIDE BY ZERO. NEVER!
Unless you're Chuck Norris, you should never divide by zero... just because you can't.
This is something one learns as soon as one learns to divide, I'm not sure when that is but I'm pretty sure is before turning 10 years old.
When one turns 20 and decided to study mathematics and has to deal with an analysis class one should be very aware of this fact, however I always say this at the beginning of the term... just to be sure that no one is going to write a division by 0. If such a thing ever happens...
I mention this because I'm currently helping a lecturer to grade his first year Chemical Engineering students and my brain is about to explode when they just casually divide by 0 when faced to a problem of the sort $\lim_{x\to0}\frac{\cos(x)-1}{2x^2}$.
I understand that if one attempts to evaluate directly with $x=0$ one simply can't since the function is not defined at that point and hence we asked only for the limit. My analysis lecturer when I was an undergrad has never been a huge fan of L'Hôpital's rule so I inherited this way of thinking and therefore my first instinct is to multiply the numerator and denominator by $\cos(x)+1$ and find a solution free of L'Hôpital's rule.
Nevertheless, engineers are happy with applying it and that's fine. The problem was that after applying it they now encounter the new problem $\lim_{x\to0}\frac{-\sin(x)}{4x}$ at which point they write again gives 0 over 0... which freaks me out again... and decide that it should be 0, thing that makes me believe they didn't get the idea of L'Hôpital's rule in the first place.
Of course some of the students handed in a decent homework and that is what one is supposed to do. But as one continues to see students writing divisions by 0 something is being done wrong. So here's the summary that encompasses everything one needs to know when found in a situation like this:
NEVER DIVIDE BY ZERO. NEVER!
Monday, 27 October 2014
Technical terms
Recently I took part in a couple of discussions that what no point whatsoever... this defines a pointless discussion, but allow me to elaborate since, paradoxically, I do have a point.
A friend of mine, from the Social Policy Department, was looking for some statistical advice for her research and came to me. She had already a very clear idea of what she wanted to do and her questions were pretty much about whether she was doing the right thing to defend her thesis. I did some research and some review of the concepts and told her she was definitely on the right track, we both were very happy with our productive meeting and went for lunch together...
At lunch we met with our friend, from the Economics Department. I don't have anything in particular against economists, in fact in my first university there were loads of them and I happen to make a lot of good friends there. However, I also learned something: There are economists who suck at maths and there are economists who are good at maths. Now, I am not a economist but as I understand it, Economics is the study of the optimum allocation of finite resources. Economics is then, not a trivial subject, and it can easily be seen how maths may be very useful. So it is natural to assume that all economists have to deal with some advanced stats at some point during their studies. I guess that based on this assumption, my friend decided to explain the economist about her ideas during lunch expecting to find an agreement... big mistake!
What happened was more or less the following. My friend explained she had done a survey and from the information gathered she had extracted some factors that were in line with the theoretical studies. Using these factors she wanted to explain a couple of variables so she was planning to do a regression analysis with the factors as the covariates. The first thing the economist said was that that was not a regression. At that point I asked why not. He said that that was not possible without really giving an argument. I rephrased the problem as the fact that we wanted to know how the factors explain the variables and even make a geometrical description of the problem and explained how a regression analysis was not only relevant but also possible and we had everything we need it to perform it. He stood on his position: That is not possible. He said that should not be called a regression since the variables we were using were factors and what were supposed to do was a "reduced rank regression". I told him I was not familiar with that technique, that maybe he could be right so I asked him to explain what a "reduced rank regression" is. He was not able to explain it, and every step he gave towards trying to get out of his problem he came up with some new technical terms: eigenvalues, time stationarity, etc.
Most of the terms he used I was familiar with, but I felt he was just giving away technical terms with the hope that at some point we would admit defeat in the sense that we didn't have the knowledge to tackle the problem. Nevertheless, I did know the terms and never conceived defeat, I looked up for the reduced rank regression technique and found out that we could have actually been able to implement the method, but it was pretty much the same as we were doing without knowing the terminology. This makes me conclude that the economist was able to identify the technique he needed in order to solve the problem but when I showed him the method he was not able to recognise it. He doesn't really know the method, he just knows when to use it.
The second discussion developed as follows. A friend from the Aerospace Engineering department came to a friend, who does Geometry, and me to try to find a solution to a problem. He wanted to know how we could find an object in space given only the distances to an instrument. We mathematicians agreed on the fact that we can't find the object unless we had more than one instrument, in fact four in space, and know the position of these instruments in space. However, the engineer wanted to know if there was a solution if we didn't know the position of the instruments. During one of our meeting another engineer listened to our conversation and decided that approach to us and told us that we were simply stupid. He argued that that problem had been solved ages ago and there were even algorithms to find the locations. I explained to him that I didn't see how that was possible and that I wanted to understand the maths behind the maths behind the problem. He insisted that our request was a stupid one and the only thing he was able to do during his "explanation" was to draw to circles on a sheet of paper but he was not capable to deduce a single equation. At this point I realised he had no idea of what he was talking about. My engineer friend asked him the algorithm then but he said someone else had it and we should ask that person. He also manage to give away another technical term: "Multilateration".
Neither my mathematician friend nor I were familiar with the term multilateration, but when I looked it up I figured out that it is precisely finding the position a point knowing the distance to four other points. Which was the problem that my mathematician friend and I were able to solve in the first place. So once again the angry engineer had an idea of the method needed to solve the problem but when seeing the maths of the method he was not able to recognise it.
So, what's the point of all this ranting? Well I came up with a bunch of key points:
1. One should not get angry if someone doesn't know something. One can politely say that a problem has been solved and if there's a technical term by which a problem is known by the experts you can introduce it.
2. Do not try finishing an argument by throwing technical terms. Using technical terms is ok as long as everybody in the discussion knows them. If not, one should introduce them.
3. If one can't do the maths of a certain technique do say so. There's nothing wrong in not knowing everything, what is vary wrong is to say people are stupid for not knowing that someone else knows it.
4. In general, obey Wheaton's Law: Don't be a dick.
A friend of mine, from the Social Policy Department, was looking for some statistical advice for her research and came to me. She had already a very clear idea of what she wanted to do and her questions were pretty much about whether she was doing the right thing to defend her thesis. I did some research and some review of the concepts and told her she was definitely on the right track, we both were very happy with our productive meeting and went for lunch together...
At lunch we met with our friend, from the Economics Department. I don't have anything in particular against economists, in fact in my first university there were loads of them and I happen to make a lot of good friends there. However, I also learned something: There are economists who suck at maths and there are economists who are good at maths. Now, I am not a economist but as I understand it, Economics is the study of the optimum allocation of finite resources. Economics is then, not a trivial subject, and it can easily be seen how maths may be very useful. So it is natural to assume that all economists have to deal with some advanced stats at some point during their studies. I guess that based on this assumption, my friend decided to explain the economist about her ideas during lunch expecting to find an agreement... big mistake!
What happened was more or less the following. My friend explained she had done a survey and from the information gathered she had extracted some factors that were in line with the theoretical studies. Using these factors she wanted to explain a couple of variables so she was planning to do a regression analysis with the factors as the covariates. The first thing the economist said was that that was not a regression. At that point I asked why not. He said that that was not possible without really giving an argument. I rephrased the problem as the fact that we wanted to know how the factors explain the variables and even make a geometrical description of the problem and explained how a regression analysis was not only relevant but also possible and we had everything we need it to perform it. He stood on his position: That is not possible. He said that should not be called a regression since the variables we were using were factors and what were supposed to do was a "reduced rank regression". I told him I was not familiar with that technique, that maybe he could be right so I asked him to explain what a "reduced rank regression" is. He was not able to explain it, and every step he gave towards trying to get out of his problem he came up with some new technical terms: eigenvalues, time stationarity, etc.
Most of the terms he used I was familiar with, but I felt he was just giving away technical terms with the hope that at some point we would admit defeat in the sense that we didn't have the knowledge to tackle the problem. Nevertheless, I did know the terms and never conceived defeat, I looked up for the reduced rank regression technique and found out that we could have actually been able to implement the method, but it was pretty much the same as we were doing without knowing the terminology. This makes me conclude that the economist was able to identify the technique he needed in order to solve the problem but when I showed him the method he was not able to recognise it. He doesn't really know the method, he just knows when to use it.
The second discussion developed as follows. A friend from the Aerospace Engineering department came to a friend, who does Geometry, and me to try to find a solution to a problem. He wanted to know how we could find an object in space given only the distances to an instrument. We mathematicians agreed on the fact that we can't find the object unless we had more than one instrument, in fact four in space, and know the position of these instruments in space. However, the engineer wanted to know if there was a solution if we didn't know the position of the instruments. During one of our meeting another engineer listened to our conversation and decided that approach to us and told us that we were simply stupid. He argued that that problem had been solved ages ago and there were even algorithms to find the locations. I explained to him that I didn't see how that was possible and that I wanted to understand the maths behind the maths behind the problem. He insisted that our request was a stupid one and the only thing he was able to do during his "explanation" was to draw to circles on a sheet of paper but he was not capable to deduce a single equation. At this point I realised he had no idea of what he was talking about. My engineer friend asked him the algorithm then but he said someone else had it and we should ask that person. He also manage to give away another technical term: "Multilateration".
Neither my mathematician friend nor I were familiar with the term multilateration, but when I looked it up I figured out that it is precisely finding the position a point knowing the distance to four other points. Which was the problem that my mathematician friend and I were able to solve in the first place. So once again the angry engineer had an idea of the method needed to solve the problem but when seeing the maths of the method he was not able to recognise it.
So, what's the point of all this ranting? Well I came up with a bunch of key points:
1. One should not get angry if someone doesn't know something. One can politely say that a problem has been solved and if there's a technical term by which a problem is known by the experts you can introduce it.
2. Do not try finishing an argument by throwing technical terms. Using technical terms is ok as long as everybody in the discussion knows them. If not, one should introduce them.
3. If one can't do the maths of a certain technique do say so. There's nothing wrong in not knowing everything, what is vary wrong is to say people are stupid for not knowing that someone else knows it.
4. In general, obey Wheaton's Law: Don't be a dick.
Tuesday, 21 October 2014
La maestría...
Encontré esta historia que escribí hace mucho tiempo cuando terminé mi maestría. Es un resumen de la historia y aquí está...
Esta parte seguro ya la conoces, pero la aventura realmente comenzó el 7 de septiembre que me fui de vaciones a las Vegas. Apenas lo logré porque me acababan de regresar mi pasaporte con ambas visas, fue una jugada arriesgada, ¡pero salió! En las Vegas, todo estuvo bien y en orden como se esperaba, (salvo que asaltaron al Neto... pero eso es otra historia) regresé el sábado de esa semana casi casi en vivo para la fiesta de despedida que organizó mi mamá.
Al día siguiente me fui a Morelia para pasar el grito pero alcancé a regresar para ir un último día a la oficina el 17 de septiembre de 2010 y no dejé de trabajar sino hasta las 15.00 hrs que me fui a una comida que organizaron en el trabajo... pero mi papá me había invitado a cenar y con la toda la pena del mundo los tuve que dejar ahí en la post comida.
El sábado 18 fue un día normal salvo el hecho de que casi no dormí y el domingo 18 fue el concierto de los 69 Eyes en lunario del auditorio nacional. Saliendo de ahí fui a cenar unos tacos cerca de la Liga Maya... regresé a mi casa a poner mis maletas y el 20 de septiembre en la madrugada tomé el avión rubo a Phoenix... luego Charlotte... y finalmente London el 21 de septiembre a las 7.00 hrs...
Tomé un taxi que por 20 pounds me dejó en casa de mi tía. Yo llevaba prácticamente dos días sin dormir, y esa noche los desquité todos. Me desperté al día siguiente como hasta las 11.00 hrs. Esa semana me estuve paseando por London, caminé por todos lados, y anduve en el metro por todos lados... me perdí, me encontré y le agarré la onda al acento londinense y al cruce de las calles.
El viernes 24 tomé el tren hacia Leamington. Ahí me recogieron Juan y Jorge y me quedé ese fin de semana en casa de Juan. Jorge pagó todo, la cena y la comida del día siguiente, y fui la primera vez que comí comida india, y me volví fan :P
El domingo 26 tomé el tren rumbo a Bath y llegué al lugar de donde te escribo ahora. Mi cuarto en John Wood Ct KA 4.1.4, Avon Street, Bath, England, BA1 1AL es como de 3x5 donde hay una cama, un escritori, un closet y una silla.... y nada más. El piso lo comparto con otros 5 individuos a saber: un chino, uno de malasia, un nigeriano, un indio y un británico. No me caen mal, pero no son nada higiénicos, el baño y la cocina siempre están hecho un asco... pero bueno, la verdad es que casi nunca los veo. Mi costumbre es nunca estar encerrado aquí, mas que en la noche para dormir. Siempre soy el primero en despertar e irme y el último en regresar, salvo los fines de semana, en que a veces el nigeriano llega después que yo porque se fue a una fiesta.
El lunes 27 fue la primera vez que caminé a la universidad. Yo vivo justo en el centro de la ciudad. La escuela está en la cima de un cerro hacia el este de la ciudad. Caminando se hacen aproximadamente 40 minutos. Antes de conocer tenía la intención de conseguir una bicicleta, pero la verdad es que el cerro está muy empinado y decidí que me iba a costar mucho trabajo venir todos los días en bici, así que mejor a pie.
La primer semana fue como un curso de inducción, de cómo usar la biblioteca (que nunca cierra!!... nunca!!), las computadoras, todas las organizaciones, etc. Me dieron también mi paquete introductorio a la maestría, que incluye las instrucciones de cómo debo escoger materias y los temarios, etc. Tuve una entrevista con el director de estudios, que es alemán y se llama Johannes Zimmer, me cayó bien, es un tipo como de 2 metros de alto. Algo que debo mencionar es que en el paquete introductorio venía una circular donde me preguntaban si me gustaría dar algún curso a los undergraduates, obviamente le pregunté a Zimmer qué podría dar yo y me recomendó los cursos de análisis... apliqué y me dieron 2 grupos. Uno de análisis 1 y uno de análisis 2. Me pagaban por eso, y pagan muy bien.
El lunes 4 de octubre empezaron las clases en forma. Yo llevaba 5 materias a saber:
Advanced Mathematical Methods. Esta clase estuvo dividida en 2, la primera parte trató sobre teoría de distribuciones, definió el espacio de Schwartz y toda el álgebra en él. Acabó definiendo las transformadas de Fourier en ese espacio y sus aplicaciones a la solución de ecuaciones diferenciales parciales. Esta parte me gustó mucho!! Pero la segunda parte del curso trató sobre análisis asintótico. Fueron básicamente 4 temas: el método de "matching" de expansiones internas y externas, la verdad no sé cómo se digan todos estos términos en español (que a lo mejor te da lo mismo... pero bueno, yo soy el que está contando la historia :P), integrales oscilatorias, el método de WKB y homogenización. De esas sólo me acuerdo del matching... todo lo demás no lo he vuelto a usar. El profesor era un ruso muy chistoso, y se me hace muy buen profesor. Creo que este fue su último semestre aquí y se va a ir a UCL en London. Aunque esta materia me gustó mucho, estuvo difícil y fue en la que peor salí el primer semestre.... pero pasé :P
Advanced Numerical Methods. Esta clase también la dividieron en dos. La primera mitad estuvo super fácil, el profesor fue Ivan Graham. El empezó desde cero enseñándonos a programar en Matlab, y en 2 meses vimos todo lo que yo vi en el ITAM en 2 semestres... yo digo que estuvo fácil porque para mi fue repaso. Después la mestra fue Melina Freitag, ella nos enseñó métodos numéricos para la solución de ecuaciones diferenciales ordinarias. Esta parte también me gustó mucho. Esta fue la materia en la que mejor me fue el semestre pasado.
Measure Theory and Integration. Esta materia también ya la había llevado en el ITAM... fue la más difícil que llevé allá. Así que me puse a estudiar como bestia salvaje y la dominé. Pensé que esta iba a ser mi mejor materia, pero fue la segunda mejor. El profesor, Nicholas Dirr, también era alemán. Ese semestre fue su último, ahora está en la University of Bristol. Esta ha sido mi materia favorita de toda la maestría :P
Applied Markov Processes and Applications. Esta estuvo padre, el profesor fue Antal Jarai, de Hungría. Vimos precisamente eso, procesos de Markov, y aplicaciones en tiempo discreto y continuo y teoría de colas (queuing theory). Me gustó :P
System Modelling and Simulation. Esta materia no era de matemáticas, era de ingeniería mecánica. Fue la que más trabajo me costó, pensé que iba a ser mi peor materia. Tuve que aprender toda la mecánica que no sabía para ponerte al tanto y poder hacer las tareas que les dejan a los de la maetría de ingeniería... qué horror!! Aprendí un buen de cosas, pero sí me costó mucho trabajo.
La mayor parte del tiempo me la pasaba estudiando y haciendo tareas en la universidad. Cuando no, por ejemplo, los viernes en la noche, me quedaba en la universidad a ver series de animación japonesa hasta tarde con otros chavos. Los martes y jueves también había alguna que otra película interesante que ver. Conocí también a varios hispano parlantes, de México, Colombia, Cuba, Argentina, Perú y España.
En el departamento de Matemáticas somos 3 maestrías: MSc in Modern Applications of Mathematics (que es la mía), MSc in Mathematical Sciences y MSc in Mathematical Biology. Nosotros somos la más grande y somos 15. Entre las otras 2 son como otros 15. Para nosotros 30 hay una oficina en el departamento de Mate en el 4W Building. Pero no todos lo ocupan. Yo sí, prácticamente es como en donde vivo, es lo que acá ocupo como ocupaba la facultad menor en el ITAM... hahaha!!
Mis compañeros (de las 3 maestrías) son mayoritariamente británicos, pero me llevo mejor con los extranjeros, particularmente con Gowri, que es de la India; Ruga, de Japón; Amin, de Algeria; Nikos, de Grecia y Elaine, de Malaysia. hay otros tres con que me llevo bien, Jack, Peter y Charlotte que son ingleses, pero no tanto como con los otros. También hay un chavo del PhD con el que me llevo muy bien, es griego y se llama Vaios.
El primer semestre fue un tanto individualista. Como que cada quien pudo armarlo como pudo. Sin embargo, el segundo semestre fue una locura y rápidamente nos empezamos a formar en equipos. Muy diferente a cómo se trabajaba allá en México, eso sí, nadie se pasa resultados, si acaso nos pasamos un tip que ayude al otro a resolver el problema. Completamente a otro nivel también.
En el segundo semestre mis materias fueron:
Mathematical Modelling and Industrial Mathematics. Imagina que el profesor era Snape de Harry Potter... igualito!! con todo y el acento inglés!! hahaha... El chiste de esta clase era leer algo y escribir una ecuación diferencial parcial sobre el párrafo y luego resolverla... pero era pésimo profesor!!! tuve que leer un buen para hacer las tareas... me hice a migo de la chica que está haciendo el PhD con él y pues ella me ayudaba a veces. Ella es Andrea, de España y me cae muy bien... ahorita se fue a unas conferencias en Amsterdam.
Topic Review of Applied Mathematics. Esta materia es muy rara, nos dieron clase de teoría de redes, problemas inversos y dinámica molecular y después cada quién escogió un tema, escribió un paper y luego hizo una presentación. Yo escogí sobre teoría molecular la teoría de transición de estado... está interesante... y todos opinan que mi presentación fue muy buena... pero eso ya lo veremos.
Scientific Computing. Esta materia se trató de programar en FORTRAN... lo odio!!!! Llegué tarde al examen... por esa razón, no lo pasé... pero me desquité en el trabajo... qu eme fue muy bien... pero es horrible. Aún así, acepto que es interesante, una de las cosas que me parece más interesante es el hecho de programar para que distintas computadoras trabajen sobre un mismo problema, parallel computing. Está muy interesante, pero la verdad el profesor y yo nunca hicimos click en la forma de programar.
Applied Probability and Finance. Se trató más bien de programación dinámica. Está fue la materia más fácil de toda la mestría. Era de esperarse porque la llevé con alumnos de lo que sería sexto semestre en el ITAM... pero no pensé que fuera a estar tan fácil.
Functional Analysis. Originalmente quería llevar Martigale Theory, pero se empalmaba con todo... así que metí esta. Esta materia me gustó. Yo digo que el examen estaba fácil, pero tenías que pensar mucho y pues a nadie le dio tiempo de terminar... a ver como nos va.
Para este semestre de 2 grupos de probabilidad y uno de análisis 1. Me gustó, pero a la fecha no he terminado de calificar todas sus tareas :S Espero acabar mañana.
Acabando las clases, un grupo de amigos y yo nos fuimos de vacaciones a Cambridge y a Oxford... y regresamos a exámenes...
Friday, 26 September 2014
Proportions
So I found this tweet the other day:
I obviously think is a great question... but I got stuck in given a power of ten, say $10^p$, how many numbers are there that are multiples of three and their first digit is three? I believe the answer to this question, and the same but with 7, will give the answer to the problem.
About 1/3? Excluding 1st digit 0, 1 Proof? @jamestanton What proportion of +ve integers are multiple of 1st digit? pic.twitter.com/3DybSxVheE
— Republic of Math (@republicofmath) 18. September 2014
I obviously think is a great question... but I got stuck in given a power of ten, say $10^p$, how many numbers are there that are multiples of three and their first digit is three? I believe the answer to this question, and the same but with 7, will give the answer to the problem.
Sunday, 31 August 2014
The Ice Bucket Challenge
The first time I saw a video of someone doing the ice bucket challenge was British Karl's video. I thought it was awesome and I thought was one of those ridiculous things people in England do for charity so very often (like hitch hiking to Paris or eating burritos in all Mission Burritos in England). Well, British Karl happened to challenge Chinese Carl to do it and in turn he challenged me.
I wanted to do it but he challenged me exactly one day before I was going on holidays with my mum and wasn't able to do my video. I went travelling in Europe for two weeks, reason for which I haven't written anything lately, and thought nobody would give a damn about the challenge when I came back. I was so wrong! 2 weeks later the ice bucket challenge was an international sensation! I got another challenge by Katy at the end of the month.
So I decided to take my opportunity and so I did. Here's my video.
As I said at the beginning, I think of it as one of the things people do for charity so very often. In a certain way, people in the maths department kept doing it that way and most of them kept donating for their favourite cause. However, I think in Mexico it seemed like a big deal for many haters. I believe their argument has to do with the shortage of water of certain communities and we were just using it for a stupid challenge... and well, they are not wrong.
Having said that, I consider myself a very "green" person and I consciously try wasting less water, generate less solid wastes, and in general have a lower carbon footprint than the average user in my situation. I can't back up my intentions with actual data, but that's not the point here, what I want to say is that that was something I thought from the beginning and that's why I decided to do the challenge with water that was already there.
I don't believe (in the sense of Reservoir Dogs's Mr. Pink) doing stuff for charity... unless it is actually donating or doing the real science. I didn't do the ice bucket challenge because I felt I was raising awareness of the ALS disease, I did it because I thought it was fun.
I wanted to do it but he challenged me exactly one day before I was going on holidays with my mum and wasn't able to do my video. I went travelling in Europe for two weeks, reason for which I haven't written anything lately, and thought nobody would give a damn about the challenge when I came back. I was so wrong! 2 weeks later the ice bucket challenge was an international sensation! I got another challenge by Katy at the end of the month.
So I decided to take my opportunity and so I did. Here's my video.
As I said at the beginning, I think of it as one of the things people do for charity so very often. In a certain way, people in the maths department kept doing it that way and most of them kept donating for their favourite cause. However, I think in Mexico it seemed like a big deal for many haters. I believe their argument has to do with the shortage of water of certain communities and we were just using it for a stupid challenge... and well, they are not wrong.
Having said that, I consider myself a very "green" person and I consciously try wasting less water, generate less solid wastes, and in general have a lower carbon footprint than the average user in my situation. I can't back up my intentions with actual data, but that's not the point here, what I want to say is that that was something I thought from the beginning and that's why I decided to do the challenge with water that was already there.
It would have been already freezing cold had it been winter, but even during the British summer you may say is not that cold, so I did put some ice on it.
I don't believe (in the sense of Reservoir Dogs's Mr. Pink) doing stuff for charity... unless it is actually donating or doing the real science. I didn't do the ice bucket challenge because I felt I was raising awareness of the ALS disease, I did it because I thought it was fun.
Tuesday, 29 July 2014
Travelling nearly lightspeed
I'm about to finish reading Why does $E=mc^2$? by Brian Cox and Jeff Forshaw (You may buy it here ). I must say it is not a very good book if you're not already a good mathematician that knows nothing about physics, otherwise I think they just tried too hard in explaining the concepts in a very abstract way without using equations that feels utterly complicated and vague language.
Having said that, I find it a very interesting book. One of the most interesting fact that I got from it is that the $c$ in Einstein's most famous formula is not the speed of light from first principle, that's just a conclusion achieved from experimentation. The $c$ is actually the speed limit at which mass-less particles must travel under the special relativity assumptions, and it must be the same speed regardless of how or who is measuring it. Since apparently photons are mass-less we have to conclude that $c$, the universal speed limit, is the speed of light.
This brings me to my point, which is just a rant about how it feels weird when they break laws of physics in action films. I'm not complaining about they don't respect them in the films, I love action films and I am expecting to see some unreal stuff in there, that's basically what I am paying for. My point is that sometimes it feels weird. I am going to put a couple of examples before getting to my point.
Consider when Steve Rogers in training some boxing in Marvel's Avengers Assemble, while he's punching the bag he recalls his war stories with his team and losing his mind he ends throwing that one punch that sends the bag flying away. The scene is obviously not real, but it still feels ok. I like to thinks that because we know Captain Rogers is capable of doing inhuman feats he has the strength to send the bag flying away and the bag follows the expected intuitive parabolic trajectory. If the trajectory is not parabolic the feel of the scene would not be the same, just as happens with the Crouching Tiger Hidden Dragon film.
Again, this doesn't mean I'm complaining, or that the film is bad, I'm just saying that the changing the laws of physics creates in the audience a weird sensation. But what happens when we're not used to some things happening and still the film decides to fuck physics just because. This happened to me when I saw Star Trek: Into Darkness.
I believe the the Star Trek films are just awesome. However the doubt still haunts me, when the Vengeance fires on the Enterprise it makes a hole on the ship. The next thing that happens is that a lot of stuff escapes from that hole, that's understandable because of the change in pressure but that doesn't mean that jumping from a ship travelling nearly at the speed of light is going to stop you. If one does jump from a ship in space, since friction is basically non existent, then one should have the same speed with respect to the ship. Especially if one's jumping nearly lightspeed because one can't jump faster.
The point is that I felt weird when people flew out and back of the ship, I think they should have flown just out perpendicular to the tangential plane of the ship at the hole. Jumping from a spaceship is essentially different than jumping off a train. At least that's what I feel, however I have never flown at lightspeed or close to that, anyways... I will continue enjoying action films with or without physics misconceptions, and the next one comes this week!
Having said that, I find it a very interesting book. One of the most interesting fact that I got from it is that the $c$ in Einstein's most famous formula is not the speed of light from first principle, that's just a conclusion achieved from experimentation. The $c$ is actually the speed limit at which mass-less particles must travel under the special relativity assumptions, and it must be the same speed regardless of how or who is measuring it. Since apparently photons are mass-less we have to conclude that $c$, the universal speed limit, is the speed of light.
This brings me to my point, which is just a rant about how it feels weird when they break laws of physics in action films. I'm not complaining about they don't respect them in the films, I love action films and I am expecting to see some unreal stuff in there, that's basically what I am paying for. My point is that sometimes it feels weird. I am going to put a couple of examples before getting to my point.
Consider when Steve Rogers in training some boxing in Marvel's Avengers Assemble, while he's punching the bag he recalls his war stories with his team and losing his mind he ends throwing that one punch that sends the bag flying away. The scene is obviously not real, but it still feels ok. I like to thinks that because we know Captain Rogers is capable of doing inhuman feats he has the strength to send the bag flying away and the bag follows the expected intuitive parabolic trajectory. If the trajectory is not parabolic the feel of the scene would not be the same, just as happens with the Crouching Tiger Hidden Dragon film.
Again, this doesn't mean I'm complaining, or that the film is bad, I'm just saying that the changing the laws of physics creates in the audience a weird sensation. But what happens when we're not used to some things happening and still the film decides to fuck physics just because. This happened to me when I saw Star Trek: Into Darkness.
I believe the the Star Trek films are just awesome. However the doubt still haunts me, when the Vengeance fires on the Enterprise it makes a hole on the ship. The next thing that happens is that a lot of stuff escapes from that hole, that's understandable because of the change in pressure but that doesn't mean that jumping from a ship travelling nearly at the speed of light is going to stop you. If one does jump from a ship in space, since friction is basically non existent, then one should have the same speed with respect to the ship. Especially if one's jumping nearly lightspeed because one can't jump faster.
The point is that I felt weird when people flew out and back of the ship, I think they should have flown just out perpendicular to the tangential plane of the ship at the hole. Jumping from a spaceship is essentially different than jumping off a train. At least that's what I feel, however I have never flown at lightspeed or close to that, anyways... I will continue enjoying action films with or without physics misconceptions, and the next one comes this week!
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