#197 how to make a matrix part of user defined function

[dan hayes]

for example i want to make a function of a matrix so i define

(fmat(matc):=disp(]matc]),fmat(matb));
And it gives edrroneous error mismatched parentheses.
On another occasion it did not gives this bogus error message but came out with wrong number of indices . What is wrong so how do i make a function of a matrix

[dan hayes]

ofcourse that is just a simple example. the actual desire is to make a much more involved function as is where i got the first error message of "wrong number of indices"

[Stavros Macrakis]

I don't understand what you mean by "make a function of a matrix".
A Maxima variable can be assigned or bound to a matrix just like anything else.

Of course (fmat(matc):=disp(]matc]),fmat(matb)) has mismatched parentheses and gives a sensible (not bogus) error message. Surely you meant (fmat(matc):=disp([matc]),fmat(matb)), but I'm not sure why you wrote that rather than say (fmat(matc):=disp(matc),fmat(matb)).

By the way, writing multiple commands on one line like that is a bit less clear than writing it on multiple lines as e.g.:

fmat(matc):=disp(matc)$
fmat(matb);

[dan hayes]

What i meant is in a user defined function using the entire matrix as an argument of my personal user defined function. I just used fmat(matrix):= .....
Where matrix could be any matrix. I need to use the whole matrix not just part of it.

[Stavros Macrakis]

A matrix is a value like any other value. For example:

~~~
normmat(M):=
block([r,c,d],
r: length(M),
c: length(M[1]),
d: determinant(M),
if d=0 then error("normmat needs det(M) to be nonzero"),
M/abs(d)^(1/r) )$

ee: matrix([1,2],[3,4]);
normmat(ee) =>
matrix([sqrt(2),2^(3/2)],[3*sqrt(2),2^(5/2)])
determinant(%) => -1
~~~