topic Re: SAS PROC IML AND SQL under precision matrix product in SAS/IML Software and Matrix Computations

SAS PROC IML AND SQL under precision matrix product

LineMoon — Wed, 03 Feb 2016 21:12:50 GMT

Hello,

I would like to konw which method give the best result for the matrix with the number between 0 et 1:

==> I have two matrix A and B, 0<=Aij<=1, 0<= Bij<=1

Which metho gives the best results :

1- IML Proc

2- proc sql

do i=1 to L;

proc sql;
create table prod as
select (...)+(....) as Vi
t1 m ,Tran_t2 n;
quit;

end;

Any documentation for that are welcomed

Re: SAS PROC IML AND SQL under precision matrix product

Rick_SAS — Wed, 03 Feb 2016 21:45:34 GMT

For matrix computations, use IML.

Your title says "matrix product," by which I assume you want the standard matrix multiplication:

C = A*B;

However, read this article "Ways to multiply in the SAS/IML language" if you want a different product.

Re: SAS PROC IML AND SQL under precision matrix product

LineMoon — Wed, 03 Feb 2016 22:27:14 GMT

Thank you for your answer.

Yes, I want to do C=A*B

But, I can use IML proc or SQL proc , I have a small number.

Please, which method (IML or SQL) is better for the small number ?

Re: SAS PROC IML AND SQL under precision matrix product

Rick_SAS — Wed, 03 Feb 2016 23:54:16 GMT

As I said, you should use IML for matrix computations.

All SAS procedures use double precision computations. If your numbers are so small that you think the computation will result in a numerical overflow or underflow, it probably doesn't make a difference how you perform the computation. If you post the data and a sample program, we might be able to say more.

Re: SAS PROC IML AND SQL under precision matrix product

Ksharp — Thu, 04 Feb 2016 07:58:41 GMT

For the precise problem , you'd better use IML's function XMULT() to calculate Matrix Product.

z = xmult(x,y); 
print z;

Look like FORMAT is not good for displaying precision.

Re: SAS PROC IML AND SQL under precision matrix product

LineMoon — Sun, 07 Feb 2016 11:43:34 GMT

Thank you for your message.

As an exemple,

You can take

A= (Aij)==> 0<Aij<1

B = (Bij)==> 0<Bij<1

Methode 1: Using IML proc

C=A*B

Method 2: Using SQl poc

C= A*transpose(B)

Re: SAS PROC IML AND SQL under precision matrix product

LineMoon — Sun, 07 Feb 2016 11:46:15 GMT

Thank you for your answer.

It is a good idea.

What's about the results found by sql proc ? C=A*transpose(B)