Example:
How to use Lapack on the IBM-cluster

The program below can be compiled and linked, either with ATLAS or with Lapack. It works both in 32 and 64 bit mode.

To compile and link with Lapack:

xlf_r linear.f -L/usr/local/lib -llapack -lessl

 

To compile and link with ATLAS

xlf_r linear.f -L/usr/local/ATLAS/lib -llapack -lcblas -lf77blas -latlas

The program linear.f

       program linear
       parameter (isize=3)
       external sgesv

       real A(isize,isize), b(isize), AT(isize*isize)
       integer i, j, c1, c2, pivot(isize), ok

       
       data A /3.1,  1.3, -5.7,
     &         1.0, -6.9,  5.8,
     &         3.4,  7.2, -8.8/
      
       data b / -1.3, -0.1, 1.8 /

C      Transpose
       do 100, i=1,isize
         do 101, j=1,isize
           AT(j+isize*(i-1)) = A(i,j)
101      continue
100    continue

       c1 = isize
       c2 = 1
       call sgesv(c1, c2, AT, c1, pivot, b, c1, ok)

C      Should output: 1.0 1.0 1.0
       write (*,'(3f4.1)') b(:)
   
       end