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26 lines
575 B
Fortran
26 lines
575 B
Fortran
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subroutine inversestep(vec,n)
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implicit none
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integer n
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real vec(n)
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integer half, k
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half=int(n/2.0)
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do k=1,half,1
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vec(k)=(sqrt(3.0)+1.0)/sqrt(2.0) * vec(k)
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vec(k+half)=(sqrt(3.0)-1.0)/sqrt(2.0) * vec(k+half)
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enddo
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do k=1,half-1,1
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vec(k)=vec(k)+vec(half+k+1)
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enddo
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vec(half)=vec(half)+vec(half+1)
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vec(half+1)=vec(half+1)+sqrt(3.0)/4.0*vec(1)+ &
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(sqrt(3.0)-2)/4.0*vec(half)
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do k=2,half,1
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vec(half+k)=vec(half+k)+sqrt(3.0)/4.0*vec(k)+ &
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(sqrt(3.0)-2)/4.0*vec(k-1)
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enddo
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do k=1,half,1
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vec(k)=vec(k)-sqrt(3.0)*vec(half+k)
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enddo
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end subroutine
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