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POInfinite loop in Fortran
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copied!<p>This is my code in Fortran 90</p> <pre><code>program final implicit none real, dimension(421,422) :: a real :: temp,factor real, dimension (421) :: soln integer :: i, rmax, pivot, row,n, O,P,COL,k,a_j,n2,a_i,t open(unit=177241,file="input_21.txt",status="old") open(unit=20,file="output.txt",status="unknown") do i =1,421 read (177241,*) (a(i,:)) end do do i = 1,421 print *,a(i,13) end do do T=1,421 n=421 a_i=n n2=422 a_j=n2 !pivoting do pivot = T,n-1 print *, 'pivot=',pivot rmax = pivot do row = pivot,a_i if (ABS(a(rmax,pivot)) < ABS(a(row,pivot)) ) then rmax=row end if end do if (rmax /= pivot) then do k=1, a_j temp = a(rmax,k) a(rmax,k) = a(pivot,k) a(pivot,k) = temp end do end if !elimination do row = pivot+1, n if ( a(pivot,pivot) /= 0 ) then factor = (a(row,pivot)) / (a(pivot,pivot)) print *,'factor=',factor do col = 1, n2 a(row, col) = a(row,col) - a(pivot,col) * factor print *,'a=',a(row,col) end do end if end do end do end do !back-substitution soln(n2) = 0 do o=n,1,-1 do p=n2,o+1,-1 a(o,n2) = a(o,n2) - soln(p)*a(o,p) end do soln(o) = a(o,n2) / a(o,o) end do do i=1,n print *,soln(i) write (121,*) soln(i) end do end program final </code></pre> <p>The input file is 441x442 matrix txt file. I think this can read that input file but it's going to be a infinite loop on here</p> <pre><code>if ( a(pivot,pivot) /= 0 ) then factor = (a(row,pivot)) / (a(pivot,pivot)) print *,'factor=',factor do col = 1, n2 a(row, col) = a(row,col) - a(pivot,col) * factor </code></pre> <p>How can I solve this problem?</p>

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