Ghhhb, Fortran - rextester

Ghhhb

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! gauss elimination with partial pivoting (backward substitution)
 Real a(10,10),b(10),x(10),pivot,sum
 Integer i,j,k,n,p
 Write(*,*)'enter the dimension of the matrix'
 Read(*,*)n
 Write(*,*)'enter the co efficient of the equation in mayrix form,input values row wise'
 Do i=1,n
 Read(*,*)(a(i,j),j=1,n),b(i)     !read the matrix
 End do
 Write(*,*)' matrix form by the coefficient of the eqn is'
 Do i=1,n       !write the matrix
 Write(*,*)(a(i,j),j=1,n)
 End do
 Write(*,*)' and the vector B is'
 Do i=1,n
 Write(*,*)b(i)
 End do
 Do i=1,n    !loop begins for gauss elimination
 max=abs(a(i,i))    !pivoting starts here
 d=i
 Do j=i+1,n
 If(abs(a(j,i)).gt.max)then
 max=abs(a(j,i))
 p=j
 Do k=1,n    !interchange row
 temp1=a(p,k)
 a(p,k)=a(d,k)
 a(d,k)=temp1
 End do
 temp2=b(p)
 b(p)=b(d)
 b(d)=temp2
 pivot=a(p,d)/a(d,d)
 Do k=1,n
 a(p,k)=a(p,k)-pivot*a(d,k)
 End do
 b(p)=b(p)-pivot*b(d)
 Else
 pivot=a(j,d)/a(d,d)
 Do k=1,n
 a(j,k)=a(j,k)-pivot*a(d,k)
 End do
 b(j)=b(j)-pivot*b(d)
 End if
 End do
 End do
 Write(*,*)'triangular matrix after gauss elimination is'
 Do i=1,n
 Write(*,*)(a(i,j)j=1,n)
 End do
 Write(*,*)'corresponding B vector is'
 Do i=1,n
 Write(*,*)b(i)
 End do
 Do i=n,1,-1  !back substitution
 sum=0.0
 Do j=i+1,n
 sum=sum+a(i,j)*x(j)
 End do
 x(i)=(b(i)-sum)/a(i,i)
 End do
 Write(*,*)'solutionz of the liner eqn'
 Do i=1,n
 Write(*,10)i,x(i)
 End do
10 format('X(',I3,')=',f10.5)
 Stop
 End

Show compiler warnings [ - ] Show input
Compilation time: 0.12 sec, absolute service time: 0,25 sec

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Error(s):

374322/source.f:49:18:

  Write(*,*)(a(i,j)j=1,n)
                  1
Error: Expected a right parenthesis in expression at (1)
374322/source.f:27:10:

  a(p,k)=a(d,k)
          1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:28:3:

  a(d,k)=temp1
   1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:31:8:

  b(p)=b(d)
        1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:32:3:

  b(d)=temp2
   1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:33:16:

  pivot=a(p,d)/a(d,d)
                1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:33:18:

  pivot=a(p,d)/a(d,d)
                  1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:33:11:

  pivot=a(p,d)/a(d,d)
           1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:35:23:

  a(p,k)=a(p,k)-pivot*a(d,k)
                       1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:37:19:

  b(p)=b(p)-pivot*b(d)
                   1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:39:16:

  pivot=a(j,d)/a(d,d)
                1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:39:18:

  pivot=a(j,d)/a(d,d)
                  1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:39:11:

  pivot=a(j,d)/a(d,d)
           1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:41:23:

  a(j,k)=a(j,k)-pivot*a(d,k)
                       1
Warning: Legacy Extension: REAL array index at (1)
374322/source.f:43:19:

  b(j)=b(j)-pivot*b(d)
                   1
Warning: Legacy Extension: REAL array index at (1)

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