Thursday, March 08, 2007

[SW] MathCast-- Equation Editor

MathCast is an open and protable software (green software) for equation edition. It saves me from MathType, because I have no money to purchase MathType... Orz

Of course, you can not expect that MathCast can replace all the excellent capabilities of MathType. It is still good enough, however, for usual applications.

[SW] Maxima-- test of matrix manipulation

Wow, what a big matix...

This is my first idea when I saw the results from Maxima. I typed the matrix in textfile, then open it with Maxima. Here are some results.

You can get this result by typing

If we use invert command to inverse the previous matrix, then here is the inverted matrix

Column 1

Column 2

Column 3


I think maybe there are some tricks I have not known, or I have to do the manipulation with my hands and pencil. O__O

Saturday, March 03, 2007

[Heli] Inverted Flight Improvement

Yes, I did the really inverted flight with the T-rex 450SE!

Just in today's afternoon, I and Chih-sen went to the field for the flight. It is still quite challenging to me to inverted the T-rex. I can not pull the control stick precisely, so occasionally some kind of unexpected motion happens when the T-rex is pitched down to be inverted.

I did some ugly pitching-down manoeuvres, and it made me very tense. Suddenly, in one of the inverted flight, I can see the vehicle clearly. It became easier for me to control it, just like what I always do in the simulator!!

It is a encourage to me. Good job today!

[SW] Static local variables in Scilab

I rewrote my C code program into Scilab. When executation, however, I found there are some errors about variables undefined.

After some check, I figured out that might be the problem of "static local variables".

Here are 2 messages I found in Scilab newsgroup:
static local variables in Scilab

I don't want to use global variable declaration. It's not a good news for me that I can not declare static local variables in Scilab... :-(

Thursday, March 01, 2007

[SW] Maxima-- A Computer Algebra System


Several days ago, I was trying to derive an inverse of a 3 by 3 matrix with its mathematical symbols. It's really a tedious work. What might be worse is aftering the horrible manipulation, one can not to be sure if the result is correct!

Now, the Maxima looks like the savior. I think I would like to try it and then write down the test result.

[SW] Scilab

Scilab Homepage

I downloaded it several months ago, but haven't spend time to understand it yet.

These days I encountered some problem in my Kalman Filter C code. For 2 by 2 matrix, everything is fine. When I rewrote the program for 3 by 3 case, however, it went overflow with causes I cannot figure out... Orz

Therefore, I think it is necessary to write the code in something like Matlab. Open and free software occurred to me, and it is the downloaded Scilab.

Hope I can get familiar with it as soon as possible, or my research progress will be delayed more. :-p

Here is a homepage including informations and tutorial materials about Scilab:

Another basic tutorial: (added at 2009/05/22)
Master Scilab! by Finn Haugen