The e^x joke, revisited

The e^x joke is probably one of the most classical geek jokes of the history. I remember my maths teacher at high school telling it to us when we were studying derivation. And a couple of years later, my calculus teacher at the school also told it to use. I guess that at that point of our lives we all knew it, but it’s always good fun hearing your teacher telling a joke at a lecture (funnier if it’s a geek joke).

Today I found a revisited version of the e^x joke, which is even funnier. But understanding it requires that you first know the classical version, so here it goes:

There was a great party in the maths world. All the functions were chatting, dancing and laughing. Suddenly, a malicious differential operator appeared at the party.

-Mwahahahaha, I’m d/dx. I’m going to derives you!

All the functions ran trying to flee the operator. All the functions except one.

-Who are you that dare to defy me?-asked d/dx.

-I am e^x.

And here goes the revisited version:

A scared x^2 function runs scared down the street. Suddenly she finds e^x.

-What’s the matter?-asks the exponential function.

-At the next street is a differential operator. If he derives me I will disappear!

-Don’t worry. I will stop him!

e^x walks towards the operator and says:

-It’s over! I’m e^x and I’m here to stop you!

And the operator replies:

-Hello e^x. I’m d/dt.


I wanted to post a link to the place where I read it, but I was just surfing the web and I don’t remember where i saw it.

I hope you enjoyed the new version of this classical joke… and that you help to spread it. You can also leave a comment giving your opinion by using the button that is at the upper-right corner of the post or by clicking the title and scrolling down. I am new to blogging and all the suggestions or ideas will be very helpful 😉

Quadcopter replica of the Millenium Falcon

An RC hobbyist called Oliver C has modded a RC quadcopter into a functional Millenium Falcon replica. To construct the hull he used expanded polystyrene which, in the spite of been heavier than the classical expanded polypropylene, is also much stronger.

Quadcopter replica of the Millenium Falcon by Oliver C

The extra weight reduces significantly the performance of the quadcopter. It can only reach the 35% of the speed than the bare quadcopter is capable of, and the battery time is reduced from 8 to 5 minutes. Anyway, the feeling of being at the controls of the legendary Millenium Falcon greatly compensates it.

Oliver has also created a big imgur album where he illustrates the whole creation project. From the design to the first test flights. I strongly recommend you to read it. Currently Oliver is working on his next project, a TIE Fighter.

And… what do you think about this quadcopter? Comments will be welcome!



Construction gallery:

Compressorhead: Robots playing rock

I know that these guys have been rocking around for some years, but as an engineer and amateur musician I couldn’t resist the temptation of writing about them in this blog. Compressorhead is a rock/metal band where all the members are robots.


As if this were not enough awesomeness they also sound pretty decent (specially for being robots) and, this is what I find more amazing, they headbang while playing their music.

But the story of Compressorhead doesn’t limit to a few performances at local clubs. They have gigs with lots of people as you can see in the next picture.


Of course they are still far from a human performer and they sound a bit mechanic but anyway I think that they are amazing. Playing a musical instrument requires very subtle and precise movements and seeing a robot capable of doing it makes me wonder what will the future bring to us. OK, it is true that there are robots being used as a surgeon assistant and they probably are even more subtle and precise than these. But I think that Compressorhead have also another virtue: They catch the “spirit” of a rock band perfectly with all their movements and headbanging.



Full gig:

NASA flickr gallery, tons of amazing pictures

I have always felt fascinated about the space. It may be because when I was a child I was rased watching sci-fi movies and series (Star Trek, Star Wars, Lost in Space…).

The night sky has always atracted me with it’s stars, constellations, planets and satellites. Thinking about all these things moving around the universe gives me the feeling of how small I am, and I find this feeling pleasant since it gets me in touch with the nature.

Therefore space exploration, as I see it, is one of the biggest adventures of our era. All he people that have worked to make it possible deserve our respect since they have made possible the impossible: To get free from the limits of our planet, to boldly go where no man (or woman) has gone before.

If you (like me) find all this stuff fascinating I’m sure that you will love the NASA flickr gallery. It collects a huge amount of photographs from all the space programs. There you can find pictures of spacecraft and program logos, but also impressive astronomical phenomenons like nebulas or galaxies.

The NASA has done a really nice job collecting all this media and making it available to us, so you should definitely check it out. Even if you are not a space geek I am sure that you will enjoy it!


Source: NASA on The Commons

[How To] Set the transparency of a MATLAB plot

Some days ago I was trying to generate a graphic of the projected EIRP over Spain using a MATLAB plot. I wanted to superimpose my results on a map I had found on the Internet, but I was unable of making the picture translucent.

MATLAB plot showing EIRP projected over Spain

Final result

Map of Spain

Map of Spain

EIRP plot

EIRP plot

This is a very common procedure when dealing with layers on a graphical editor software like GIMP or Photoshop. There’s usually a parameter called “opacity” that let’s you set the transparency of the layer in a MATLAB plot.

Given this, I was sure that MATLAB would have a similar option. After some time of googling I found it. After plotting some data you can use a handle to the plot for setting a parameter called “AlphaData”. This parameter represents the opacity of the plot in the range [0,1] (where 0 means “Invisible” and 1 means “No transparency at all”).

So you can do something like this:

imshow('Map.jpg'); hold on;
PIREhand = imagesc( ... );
set(PIREhand, 'AlphaData', 0.6);


Map Image: desfaziendoentuertos

Raspberry Pi 2 is now on sale

It has recently been announced that the new Raspberry Pi 2 is on sale since today at the price of $35.

Raspberry Pi 2

The pocket computer comes with a 900MHz quad-core ARM Cortex-A7 CPU and 1GB LPDDR2 SDRAM. It is also fully compatible with Raspberry Pi 1. But the news don’t end here. There will be a Windows 10 version tailored for Raspberry Pi 2 and it will be free to use for developers thanks to the Windows Developer Program for the Internet of Things.

You can find more info about specs and suppliers here.



Good News!

Hello everybody!

Today I have two good news to announce. The first one is that this website is finally open. The site has been on-line for almost two months but I was performing some creation work. Now I remove the “Site under maintenance message” and publish this first post. There may still be some minor changes, but they shouldn’t affect to the functionality.

This site is created with the idea of publishing stuff related to my career (Click here to see my bio) so you’ll find articles and publications in the “static” part of the web page, but you will also find engineering-related posts in this blog. The topics will be very diverse and they will range from coding tips to technology news or mathematical paradoxes (just to list some).

The second good new is that some months ago I presented an abstract to the CMN2015 (Congress on Numerical Methods of the Engineering) and yesterday I received an e-mail informing me that the abstract had been accepted! I am very excited about this since it’s my first congress up to now.