ADAS Subroutine nfitsp
SUBROUTINE NFITSP(X,XA,N,YAA,Y,DY,I0,C1,C2,C3,C4,ISW) IMPLICIT REAL*8(A-H,O-Z) C----------------------------------------------------------------------- C PURPOSE: PERFORM SPLINE INTERPOLATION C C INPUT C X = REQUIRED X-VALUE C XA(I) = X-VALUES C N = NUMBER OF VALUES C YAA(I) = Y-VALUES (POSSIBLY STORED AS MULTIPLE SETS) C I0 = STARTING INDEX(-1) IN YAA ARRAY OF REQUIRED INPUT SET C C1(I,J) = 1ST SPLINE COEFFICIENT PRECURSOR C C2(I,J) = 2ND SPLINE COEFFICIENT PRECURSOR C C3(I,J) = 3RD SPLINE COEFFICIENT PRECURSOR C C4(I,J) = 4TH SPLINE COEFFICIENT PRECURSOR C ISW = .LE.0 ORDINARY SPLINE INTERPOLATION C = .GT.0 LOGARITHMIC SPLINE INTERPOLATION C OUTPUT C Y = RETURNED Y-VALUE C DY = RETURNED DERIVATIVE C C C ********* ************** C----------------------------------------------------------------------- C IDL-UNIX CONVERSION: C C VERSION: 1.1 DATE: 01/10/96 C MODIFIED: WILLIAM OSBORN C - FIRST WRITTEN. NO CHANGES. C C VERSION: 1.2 DATE: 15/05/07 C MODIFIED: Allan Whiteford C - Updated comments as part of subroutine C documentation production. C C----------------------------------------------------------------------- C----------------------------------------------------------------------- INTEGER I0, ISW, N REAL*8 C1(10,9), C2(10,9), C3(10,9) REAL*8 C4(10,9), DY, X, XA(10) REAL*8 Y, YAA(10)