ADAS Subroutine sigia
C
SUBROUTINE SIGIA ( LSETX , LPASS ,
& ALPH , ETH , ILTYP , IOPT ,
& NENIN , ENIN , SGIN ,
& LTHETA , VREL , XSEC
& )
C-----------------------------------------------------------------------
C
C ********************** FORTRAN77 SUBROUTINE: SIGIA ******************
C
C VERSION: 1.0 (ADAS91)
C
C PURPOSE: INTERPOLATES CROSS-SECTION DATA FROM AN INPUT VECTOR OF
C VALUES USING CUBIC SPLINES.
C
C EXTRAPOLATES FOR RELATIVE SPEEDS OUT OF DATA RANGE ACCORDING TO
C VARIOUS TYPES (ILTYP). LOGARITHMIC INTERPOLATION MAY BE USED
C (LPASS). SPEED ECONOMY IS POSSIBLE FOR REPEATS WITH THE SAME
C SPLINE KNOTS (LSETX).
C
C
C CALLING PROGRAM: CXTHER
C
C NOTES:
C (1) FOR ILTYP.EQ.0, EXTRAPOLATION IS AS FOLLOWS:
C
C
C SUBROUTINE:
C
C INPUT : (L*4) LSETX = .TRUE. => SPLINE NOT SET FOR THESE KNOTS
C .FLSE. => SPLINE NOT FOR THESE KNOTS
C INPUT : (L*4) LPASS = .TRUE. => DO NOT CONVERT INTO LOG10 FOR
C ENERGIES AND X-SECTS. FOR SPLINE
C .FLSE. => CONVERT INTO LOG10 FOR
C ENERGIES AND X-SECTS. FOR SPLINE
C INPUT : (R*8) ALPH = HIGH ENERGY EXTRAPOLATION PARAMETER
C INPUT : (R*8) ETH = THRESHOLD ENERGY (RYD.)
C INPUT : (I*4) ILTYP = TYPE FOR LOW AND HIGH ENERGY CROSS-
C -SECTION EXTRAPOLATION.
C INPUT : (I*4) IOPT = SPLINE END POINT CURVATURE/GRADIENT OPTION
C 1 => DDY1 = 0, DDYN = 0
C 4 => DY1 = 0 , DDYN = 0
C
C INPUT : (I*4) NENIN = NUMBER OF ENERGIES IN INPUT DATA SET
C INPUT : (R*8) ENIN() = ENERGIES (EV/AMU) IN INPUT DATA SET
C INPUT : (R*8) SGIN() = INPUT X-SECTIONS (CM2) FROM INPUT DATA SET
C 1ST.DIM: ENERGY INDEX
C INPUT : (I*4) LTHETA = NUMBER OF VALUES IN VREL VECTOR
C INPUT : (R*8) VREL() = RELATIVE SPEEDS FOR OUTPUT (CM S-1)
C
C OUTPUT: (R*8) XSEC() = OUTPUT CROSS-SECTION (CM2)
C
C (I*4) MAXENS = PARAMETER = MAX. LENGTH OF TABULAR XSECT.
C VECTOR
C (I*4) LDTHET = PARAMETER = MAX. LENGTH OF INTERNAL
C VECTORS
C (R*8) CMSAMU = PARAMETER = CONVERSION FACTOR FOR ENERGY
C (AMU) TO VELOCITY (CM S-1)
C
C (I*4) I = GENERAL INDEX
C (I*4) N = GENERAL INDEX
C (R*8) ALPH0 = LOW VELOCITY EXTRAPOLATION PARAMETER
C (R*8) EXPON = EXPONENT OF EXPONENTIAL
C (R*8) VSLOPE = HIGH VELOCITY EXTRAPOLATION PARAMETER
C (R*8) XIN() = INTERNAL SPLINE INDEPENDENT VARIABLE
C (R*8) YIN() = INTERNAL SPLINE DEPENDENT VARIABLE
C (R*8) VIN() = INTERNAL VECTOR
C (R*8) DY() = DERIVATIVES AT SPLINE KNOTS
C (R*8) XOUT() = INTERNAL OUTPUT INDEPENDENT VARIABLE
C (R*8) YOUT() = INTERNAL OUTPUT DEPENDENT VARIABLE
C (L*4) LINTRP() = .TRUE. => POINT INTERPOLATED
C = .FALSE. => POINT EXTRAPOLATED
C
C
C ROUTINES:
C ROUTINE SOURCE BRIEF DESCRIPTION
C -------------------------------------------------------------
C XXSPLE ADAS INTERPOLATES USING CUBIC SPLINES
C R8FUN1 ADAS EXTERNAL FUNCTION FOR XXSPLE
C
C
C AUTHOR: H. P. SUMMERS, UNIVERSITY OF STRATHCLYDE
C JA8.08
C TEL. 0141-553-4196
C
C DATE: 18/11/96
C
C VERSION: 1.1 DATE: 18-11-96
C MODIFIED: HUGH P. SUMMERS, UNIVERSITY OF STRATHCLYDE
C - FIRST EDITION
C
C VERSION: 1.1 DATE: 17-05-07
C MODIFIED: Allan Whiteford
C - Modified comments as part of subroutine documentation
C procedure.
C
C
C--------------------------------------------------------------------
INTEGER ILTYP, IOPT, LTHETA, NENIN
LOGICAL LPASS, LSETX
REAL*8 ALPH, ENIN(NENIN), ETH
REAL*8 SGIN(NENIN), VREL(LTHETA)
REAL*8 XSEC(LTHETA)