Re: Inverse matrix problem (with LAPACK maybe....)

[Minkyung Kersti Son]

Thank you very much!^^
I think that the condition of this matrix is very ill
because this code works well for other matrix.

       implicit none
       integer i, j
       integer,parameter :: n=19
       complex mat(n,n)
       complex,dimension(n,n) :: matA, matAinv, matI
       real dum1, dum2

       integer ipiv(n)
       integer info
       integer,parameter :: lwork=64*n
       complex work(lwork)
       external cgetrf, cgetri

       mat=cmplx(0.,0.)
       open(10,file='gauss.txt')
       do i=1,n
         do j=1,n
           read(10,*) dum1, dum2
           mat(i,j)=cmplx(dum1,dum2)
           matA(i,j)=mat(i,j)
         end do
       end do
       close(10)

       call cgetrf(n,n,mat,n,ipiv,info)

       if (info==0)then
         call cgetri(n,mat,n,ipiv,work,lwork,info)
       else
         print*, 'info=/0'
       end if

       do i=1,n
       do j=1,n
       matAinv(i,j)=mat(i,j)
       end do
       end do

       matI=matmul(matA,matAinv)

       do i=1,n
         do j=1,n
           print*, i, j, matI(i,j)
         end do
       end do

       end program


'gauss.txt' is what I attached above.

I've tried to solve this problem with changing to cgetrf(cgetri) to others:
chetrf(chetri), csytrf(csytri..).

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