root / src / gaussj.f90 @ 5
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| 1 | 1 | equemene | |
|---|---|---|---|
| 2 | 1 | equemene | SUBROUTINE gaussj(a,n,np,b,m,mp) |
| 3 | 1 | equemene | |
| 4 | 1 | equemene | IMPLICIT NONE |
| 5 | 1 | equemene | |
| 6 | 1 | equemene | INTEGER, PARAMETER :: KINT=KIND(1) |
| 7 | 1 | equemene | INTEGER, PARAMETER :: KREAL=KIND(1.0D0) |
| 8 | 1 | equemene | |
| 9 | 1 | equemene | |
| 10 | 1 | equemene | INTEGER(KINT) :: m,mp,n,np,NMAX |
| 11 | 1 | equemene | REAL(KREAL) :: a(np,np),b(np,mp) |
| 12 | 1 | equemene | PARAMETER (NMAX=50) |
| 13 | 1 | equemene | INTEGER(KINT) :: i,icol,irow,j,k,l,ll,indxc(NMAX),indxr(NMAX),ipiv(NMAX) |
| 14 | 1 | equemene | REAL(KREAL) :: big,dum,pivinv |
| 15 | 1 | equemene | do 11 j=1,n |
| 16 | 1 | equemene | ipiv(j)=0 |
| 17 | 1 | equemene | 11 continue |
| 18 | 1 | equemene | do 22 i=1,n |
| 19 | 1 | equemene | big=0.d0 |
| 20 | 1 | equemene | do 13 j=1,n |
| 21 | 1 | equemene | if(ipiv(j).ne.1)then |
| 22 | 1 | equemene | do 12 k=1,n |
| 23 | 1 | equemene | if (ipiv(k).eq.0) then |
| 24 | 1 | equemene | if (abs(a(j,k)).ge.big)then |
| 25 | 1 | equemene | big=abs(a(j,k)) |
| 26 | 1 | equemene | irow=j |
| 27 | 1 | equemene | icol=k |
| 28 | 1 | equemene | endif |
| 29 | 1 | equemene | else if (ipiv(k).gt.1) then |
| 30 | 1 | equemene | pause 'singular matrix in gaussj' |
| 31 | 1 | equemene | endif |
| 32 | 1 | equemene | 12 continue |
| 33 | 1 | equemene | endif |
| 34 | 1 | equemene | 13 continue |
| 35 | 1 | equemene | ipiv(icol)=ipiv(icol)+1 |
| 36 | 1 | equemene | if (irow.ne.icol) then |
| 37 | 1 | equemene | do 14 l=1,n |
| 38 | 1 | equemene | dum=a(irow,l) |
| 39 | 1 | equemene | a(irow,l)=a(icol,l) |
| 40 | 1 | equemene | a(icol,l)=dum |
| 41 | 1 | equemene | 14 continue |
| 42 | 1 | equemene | do 15 l=1,m |
| 43 | 1 | equemene | dum=b(irow,l) |
| 44 | 1 | equemene | b(irow,l)=b(icol,l) |
| 45 | 1 | equemene | b(icol,l)=dum |
| 46 | 1 | equemene | 15 continue |
| 47 | 1 | equemene | endif |
| 48 | 1 | equemene | indxr(i)=irow |
| 49 | 1 | equemene | indxc(i)=icol |
| 50 | 1 | equemene | if (a(icol,icol).eq.0.d0) pause 'singular matrix in gaussj' |
| 51 | 1 | equemene | pivinv=1.d0/a(icol,icol) |
| 52 | 1 | equemene | a(icol,icol)=1.d0 |
| 53 | 1 | equemene | do 16 l=1,n |
| 54 | 1 | equemene | a(icol,l)=a(icol,l)*pivinv |
| 55 | 1 | equemene | 16 continue |
| 56 | 1 | equemene | do 17 l=1,m |
| 57 | 1 | equemene | b(icol,l)=b(icol,l)*pivinv |
| 58 | 1 | equemene | 17 continue |
| 59 | 1 | equemene | do 21 ll=1,n |
| 60 | 1 | equemene | if(ll.ne.icol)then |
| 61 | 1 | equemene | dum=a(ll,icol) |
| 62 | 1 | equemene | a(ll,icol)=0.d0 |
| 63 | 1 | equemene | do 18 l=1,n |
| 64 | 1 | equemene | a(ll,l)=a(ll,l)-a(icol,l)*dum |
| 65 | 1 | equemene | 18 continue |
| 66 | 1 | equemene | do 19 l=1,m |
| 67 | 1 | equemene | b(ll,l)=b(ll,l)-b(icol,l)*dum |
| 68 | 1 | equemene | 19 continue |
| 69 | 1 | equemene | endif |
| 70 | 1 | equemene | 21 continue |
| 71 | 1 | equemene | 22 continue |
| 72 | 1 | equemene | do 24 l=n,1,-1 |
| 73 | 1 | equemene | if(indxr(l).ne.indxc(l))then |
| 74 | 1 | equemene | do 23 k=1,n |
| 75 | 1 | equemene | dum=a(k,indxr(l)) |
| 76 | 1 | equemene | a(k,indxr(l))=a(k,indxc(l)) |
| 77 | 1 | equemene | a(k,indxc(l))=dum |
| 78 | 1 | equemene | 23 continue |
| 79 | 1 | equemene | endif |
| 80 | 1 | equemene | 24 continue |
| 81 | 1 | equemene | return |
| 82 | 1 | equemene | END |