24 lines
601 B
Fortran
24 lines
601 B
Fortran
SUBROUTINE relax2(u,rhs,n)
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INTEGER n
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DOUBLE PRECISION rhs(n,n),u(n,n)
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INTEGER i,ipass,isw,j,jsw
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DOUBLE PRECISION foh2,h,h2i,res
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h=1.d0/(n-1)
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h2i=1.d0/(h*h)
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foh2=-4.d0*h2i
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jsw=1
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do 13 ipass=1,2
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isw=jsw
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do 12 j=2,n-1
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do 11 i=isw+1,n-1,2
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res=h2i*(u(i+1,j)+u(i-1,j)+u(i,j+1)+u(i,j-1)-4.d0*u(i,j))+
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*u(i,j)**2-rhs(i,j)
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u(i,j)=u(i,j)-res/(foh2+2.d0*u(i,j))
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11 continue
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isw=3-isw
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12 continue
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jsw=3-jsw
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13 continue
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return
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END
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