Can a function returns a matrix?

[Balaji.V]

hi all,
I want a function that takes matrix as input and returns a
matrix. (say, function that performs matrix multiplication) . How can I
go about this? Can anybody help me?
Balaji.V

[Chris Torek]

In article <eb**********@n ews.tiscali.fr>
Bernard Xhumga <xh****@tiscali .frwrote:

>Now [this code] is perfect ?

It seems nothing is ever *perfect* but at least it is all correct :-)

[snippage]

>double **A = malloc(r * sizeof( *A) );
if(!A)exit(1);

In a more-general-purpose routine, it would be fairly rude to exit
(with no error message, at that) here -- instead, the function
should return some sort of error indication to its caller, saying
"I was unable to allocate the memory you requested". For quite a
few purposes, simply exiting (preferably with a message first) is
sufficient, though.

A[0] = malloc(r * c * sizeof(**A) );
if(!A[0])exit(1);

This part is good enough, with the same caveat.

for(i=1; i<r; i++)
{
A[i] = A[0]+i*c;
if(!A[i])exit(1);

This test ("if(!A[i])") is unnecessary, though harmless. If A[0]
is not NULL, A[0] + i * c should never be NULL either.

>return(A);
}

[snippage]

>void f_mR(
double **A
)
{
free((void *)A[0]);
free((void *)A);
}

The two casts are unnecessary but harmless (since <stdlib.hwas
included in code I snipped above).
--
In-Real-Life: Chris Torek, Wind River Systems
Salt Lake City, UT, USA (40°39.22'N, 111°50.29'W) [phone]
email: forget about it http://web.torek.net/torek/index.html
Reading email is like searching for food in the garbage, thanks to spammers.

[Keith Thompson]

Chris Torek <no****@torek.n etwrites:

In article <eb**********@n ews.tiscali.fr>
Bernard Xhumga <xh****@tiscali .frwrote:

>>Now [this code] is perfect ?

It seems nothing is ever *perfect* but at least it is all correct :-)

[snippage]

>>double **A = malloc(r * sizeof( *A) );
if(!A)exit(1);

In a more-general-purpose routine, it would be fairly rude to exit
(with no error message, at that) here -- instead, the function
should return some sort of error indication to its caller, saying
"I was unable to allocate the memory you requested". For quite a
few purposes, simply exiting (preferably with a message first) is
sufficient, though.

[...]

And if you do want to call exit(), use exit(EXIT_FAILU RE) rather than
exit(1); the latter is non-portable, and may not indicate failure on
some systems.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Bernard Xhumga]

Thank for your help.
I have learned a lof of in few time.
Now I will try to rewrite my work.

Thank.