Mathlab Symbolic Determinat , display issues

[Maxong091]

Hi all,

I am working on a robotics problem and I have to get the determinant of a 3X3 matrix in symbolic form. The expressions are quite complex, Matlab 7.10.0 solves the expression in about 30 seconds but cannot display the answer. I would need to copy and paste this answer into another function. There does not seem to be any way to access this variable either in the command window or by saving it, without crashing the computer.



Basically

D=det(Matrix);

Now the D variable is a 1X1 sym in the workspace but I cannot access it.

Is this because the expression is too large, would Mathelatica do a better job of it?

Thanks

 

[serbring]

Hi all,

I am working on a robotics problem and I have to get the determinant of a 3X3 matrix in symbolic form. The expressions are quite complex, Matlab 7.10.0 solves the expression in about 30 seconds but cannot display the answer. I would need to copy and paste this answer into another function. There does not seem to be any way to access this variable either in the command window or by saving it, without crashing the computer.



Basically

D=det(Matrix);

Now the D variable is a 1X1 sym in the workspace but I cannot access it.

Is this because the expression is too large, would Mathelatica do a better job of it?

Thanks

may you write the message you get from matlab?

 

[Maxong091]

Hi,

This is the error message

? Error using ==> mupadmex
Error in MuPAD command:


here in red text a segment of the expression is shown then



Error in ==> sym.disp at 19
allstrs = mupadmex(X.s,0);

Error in ==> sym.display at 17
disp(X)

 

[Mech_Engineer]

What if you had the program solve the manual determinant equation instead:

$$a_{1}b_{2}c_{3}+a_{2}b_{3}c_{1}+a_{3}b_{1}c_{2}-a_{3}b_{2}c_{1}-a_{2}b_{1}c_{3}-a_{1}b_{3}c_{2}$$

 

[viscousflow]

If you had maple it would be a lot easier and faster. Matlab's symbolic toolbox is very slow and cumbersome. Or you could try Wolfram Alpha. Works almost as fast as maple (if not faster).

http://www.wolframalpha.com/