PGI User's Guide

Chapter 13. Programming Considerations for 64-Bit Environments!$omp parallel!$omp dodo i = 1, mdo j = 1, nc(i,j) = a(i,j) + b(i,j)enddoenddo!$omp dodo i=1,mdo j = 1, nd = 30000.0D0*dble(i)+dble(j)+dble(j)if(d .ne. c(i,j)) thenprint *,"err i=",i,"j=",jprint *,"c(i,j)=",c(i,j)print *,"d=",dstopendifenddoenddo!$omp end parallelprint *, "M =",M,", N =",Nprint *, "c(M,N) = ", c(m,n)endWhen compiled with the PGFORTRAN compiler using –mcmodel=medium:% pgfortran –mp –o mat mat.f –i8 –mcmodel=medium% setenv OMP_NUM_THREADS 2% matM = 16000 , N = 16000c(M,N) = 480032000.0000000Large Array and Small Memory Model in FortranThe following example uses large, dynamically-allocated arrays. The code is divided into a main andsubroutine so you could put the subroutine into a shared library. Dynamic allocation of large arrays savesspace in the size of executable and saves time initializing data. Further, the routines can be compiled with 32-bit compilers, by just decreasing the parameter size.Example 13.3. Large Array and Small Memory Model in Fortran% cat mat_allo.f90program mat_allointeger i, jinteger size, m, nparameter (size=16000)parameter (m=size,n=size)double precision, allocatable::a(:,:),b(:,:),c(:,:)allocate(a(m,n), b(m,n), c(m,n))do i = 100, m, 1do j = 100, n, 1a(i,j) = 10000.0D0 * dble(i) + dble(j)b(i,j) = 20000.0D0 * dble(i) + dble(j)enddoenddocall mat_add(a,b,c,m,n)print *, "M =",m,",N =",n173