root / synthbench / euroben-dm / mod2ci / .svn / text-base / rotf.f.svn-base @ 0:839f52ef7657
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Subroutine rotf( arg, c, s ) |
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! ---------------------------------------------------------------------- |
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! --- Recovers rotation factors c & s from 'arg' for the Givens |
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! transformation (used in rgmres). |
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! ---------------------------------------------------------------------- |
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Use numerics |
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Use floptime |
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Implicit None |
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|
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Real(l_) :: arg, c, s |
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! ---------------------------------------------------------------------- |
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If ( arg == 0.0_l_ ) Then |
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c = 0.0_l_ |
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s = 1.0_l_ |
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Else If ( Abs( arg ) < 1.0_l_ ) Then |
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s = 2.0_l_*arg |
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c = Sqrt( 1.0_l_ - s*s ) |
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flops = flops + 12 |
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Else |
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c = 2.0_l_/arg |
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s = Sqrt( 1.0_l_ - c*c ) |
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flops = flops + 12 |
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End If |
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! ---------------------------------------------------------------------- |
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End Subroutine rotf |