HIJING/hijing1_36/gauss1.F

   1 * $Id$
   2
   3 C
   4 C
   5 C*********GAUSSIAN ONE-DIMENSIONAL INTEGRATION PROGRAM*************
   6 C
   7         FUNCTION GAUSS1(F,A,B,EPS)
   8         EXTERNAL F
   9         DIMENSION W(12),X(12)
  10         DATA CONST/1.0E-12/
  11         DATA W/0.1012285,.2223810,.3137067,.3623838,.0271525,
  12      &         .0622535,0.0951585,.1246290,.1495960,.1691565,
  13      &         .1826034,.1894506/
  14         DATA X/0.9602899,.7966665,.5255324,.1834346,.9894009,
  15      &         .9445750,0.8656312,.7554044,.6178762,.4580168,
  16      &         .2816036,.0950125/
  17         SAVE
  18         DELTA=CONST*ABS(A-B)
  19         GAUSS1=0.0
  20         AA=A
  21 5       Y=B-AA
  22         IF(ABS(Y).LE.DELTA) RETURN
  23 2       BB=AA+Y
  24         C1=0.5*(AA+BB)
  25         C2=C1-AA
  26         S8=0.0
  27         S16=0.0
  28         DO 1 I=1,4
  29         U=X(I)*C2
  30 1       S8=S8+W(I)*(F(C1+U)+F(C1-U))
  31         DO 3 I=5,12
  32         U=X(I)*C2
  33 3       S16=S16+W(I)*(F(C1+U)+F(C1-U))
  34         S8=S8*C2
  35         S16=S16*C2
  36         IF(ABS(S16-S8).GT.EPS*(1.+ABS(S16))) GOTO 4
  37         GAUSS1=GAUSS1+S16
  38         AA=BB
  39         GOTO 5
  40 4       Y=0.5*Y
  41         IF(ABS(Y).GT.DELTA) GOTO 2
  42         WRITE(6,7)
  43         GAUSS1=0.0
  44         RETURN
  45 7       FORMAT(1X,'GAUSS1....TOO HIGH ACURACY REQUIRED')
  46         END