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jmc |
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C $Header: $ |
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C $Name: $ |
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# include "GAD_OPTIONS.h" |
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C-- File gad_plm_fun.F: Routines for monotone piecewise linear method. |
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C-- Contents |
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C-- o GAD_PLM_FUN_U |
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C-- o GAD_PLM_FUN_V |
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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SUBROUTINE GAD_PLM_FUN_U( |
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I ffll,ff00,ffrr, |
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O dfds) |
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C |================================================================| |
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C | PLM_FUN_U: monotone piecewise linear method. | |
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C | - uniform grid-spacing variant. | |
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C |================================================================| |
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implicit none |
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C ====================================================== arguments |
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_RL ffll,ff00,ffrr |
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_RL dfds(-1:+1) |
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C ====================================================== variables |
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_RL fell,ferr,scal |
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_RL epsil |
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PARAMETER( epsil = 1. _d -16 ) |
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dfds(-1) = ff00 - ffll |
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dfds(+1) = ffrr - ff00 |
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if (dfds(-1) * dfds(+1) .gt. 0.0 _d 0) then |
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C ======================================= calc. ll//rr edge values |
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fell = 0.5 _d 0 * (ffll + ff00) |
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ferr = 0.5 _d 0 * (ff00 + ffrr) |
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C ======================================= calc. centred derivative |
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dfds(+0) = |
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& 0.5 _d 0 * (ferr - fell) |
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C ======================================= monotonic slope-limiting |
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scal = min(abs(dfds(-1)), |
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& abs(dfds(+1))) |
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& / max(abs(dfds(+0)), epsil) |
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c & / max(abs(dfds(+0)), epsilon(ff00)) |
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scal = min(scal, 1.0 _d 0) |
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dfds(+0) = scal * dfds(+0) |
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else |
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C ======================================= flatten if local extrema |
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dfds(+0) = 0.0 _d 0 |
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end if |
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dfds(-1) = 0.5 _d 0 * dfds(-1) |
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dfds(+1) = 0.5 _d 0 * dfds(+1) |
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return |
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c end subroutine GAD_PLM_FUN_U |
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end |
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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SUBROUTINE GAD_PLM_FUN_V( |
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I ffll,ff00,ffrr, |
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I ddll,dd00,ddrr, |
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O dfds) |
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C |================================================================| |
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C | PLM_FUN_V: monotone piecewise linear method. | |
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C | - variable grid-spacing variant. | |
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C |================================================================| |
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implicit none |
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C ====================================================== arguments |
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_RL ffll,ff00,ffrr |
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_RL ddll,dd00,ddrr |
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_RL dfds(-1:+1) |
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C ====================================================== variables |
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_RL fell,ferr,scal |
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_RL epsil |
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PARAMETER( epsil = 1. _d -16 ) |
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dfds(-1) = ff00 - ffll |
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dfds(+1) = ffrr - ff00 |
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if (dfds(-1) * dfds(+1) .gt. 0.0 _d 0) then |
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C ======================================= calc. ll//rr edge values |
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fell = (dd00 * ffll + ddll * ff00) |
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& / (ddll + dd00) |
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ferr = (ddrr * ff00 + dd00 * ffrr) |
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& / (dd00 + ddrr) |
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C ======================================= calc. centred derivative |
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dfds(+0) = |
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& 0.5 _d 0 * (ferr - fell) |
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C ======================================= monotonic slope-limiting |
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scal = min(abs(dfds(-1)), |
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& abs(dfds(+1))) |
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& / max(abs(dfds(+0)), epsil) |
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c & / max(abs(dfds(+0)), epsilon(ff00)) |
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scal = min(scal, 1.0 _d 0) |
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dfds(+0) = scal * dfds(+0) |
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else |
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C ======================================= flatten if local extrema |
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dfds(+0) = 0.0 _d 0 |
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end if |
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C == !! check this |
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dfds(-1) = dfds(-1) / (ddll + dd00) * dd00 |
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dfds(+1) = dfds(+1) / (dd00 + ddrr) * dd00 |
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return |
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c end subroutine GAD_PLM_FUN_V |
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end |
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