Usings subs on matrices ?

Hi everyone,

I'm trying to substitute variables in a matrix, but I run in something a little bit weird. When using the command "C = subs(C, exp1, exp2)", the result is not the matrix that I would have had if I had done the same substitution for all elements of C. How can it be ?

[Jos (10584)]

Your question is too vague. Can you give a very small example of

1. your input
2. what you did
3. what you got as output
4. what you expected to get

Added: I do not know a command called SUBS

[Matthieu]

Hi Jos,

So my matrix C was 5x5 matrix with quite complicated expression, but to make it simple let's say that all coefficients are of the form : (xi - xj) * lp * exp where exp is a symbolic expression, xi (i=1:5) and lp are symbolic variables.

Now, I have a variable y which value is 0 and my script goes :

C = subs(C, xi, y);

which I would expect to give -xj * lp * exp, but what I actually get is lp. When I do the substitution on the expression only, I get, the right result.

Any idea ?

Answer 1

[Johannes Korsawe]

C(C==exp1) = exp2;

??