mirror of https://gitlab.com/QEF/q-e.git
45 lines
1.1 KiB
Fortran
45 lines
1.1 KiB
Fortran
!
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!---------------------------------------------------------------
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subroutine inward(y,f,g,mesh,imatch)
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!---------------------------------------------------------------
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! inward integration, charlotte froese can j phys 41,1895(1963)
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!
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use kinds, only:DP
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use ld1inc, only:ndm
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implicit none
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!
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! I/O variables
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!
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integer :: mesh, imatch
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real(DP) :: y(ndm), f(ndm), g(ndm)
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!
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! local variables
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!
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integer :: imp1, imp2, nm1, n
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real(DP) :: di, ff, expn
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real(DP) :: el(ndm),c(ndm)
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if (ndm.lt.mesh) stop ' inward : ndm .lt. mesh !!!!'
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! set up el, and c vectors
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imp1=imatch+1
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el(imp1)=10.d0*f(imp1)-12.d0
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c(imp1)=g(imp1)-f(imatch)*y(imatch)
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imp2=imatch+2
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nm1=mesh-1
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do n=imp2,nm1
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di=10.d0*f(n)-12.d0
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el(n)=di-f(n)*f(n-1)/el(n-1)
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c(n)=g(n)-c(n-1)*f(n-1)/el(n-1)
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end do
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! start with y=aexp(-ax)-b, with b="g"/f
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ff=12.d0*abs(1.d0-f(nm1))
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expn=exp(-sqrt(ff))
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y(mesh)=(c(nm1)*expn+g(nm1)*el(nm1)*(expn-1.d0)/ff)/(el(nm1)+f(mesh)*expn)
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! inward integration
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do n=nm1,imp1,-1
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y(n)=(c(n)-f(n+1)*y(n+1))/el(n)
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end do
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!
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return
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end subroutine inward
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