HIJING/hijing1_36/gauss3.F

   1 * $Id$
   2 C
   3 C
   4 C
   5         FUNCTION GAUSS3(F,A,B,EPS)
   6         EXTERNAL F
   7         DIMENSION W(12),X(12)
   8         DATA CONST/1.0E-12/
   9         DATA W/0.1012285,.2223810,.3137067,.3623838,.0271525,
  10      &         .0622535,0.0951585,.1246290,.1495960,.1691565,
  11      &         .1826034,.1894506/
  12         DATA X/0.9602899,.7966665,.5255324,.1834346,.9894009,
  13      &         .9445750,0.8656312,.7554044,.6178762,.4580168,
  14      &         .2816036,.0950125/
  15         SAVE
  16         DELTA=CONST*ABS(A-B)
  17         GAUSS3=0.0
  18         AA=A
  19 5       Y=B-AA
  20         IF(ABS(Y).LE.DELTA) RETURN
  21 2       BB=AA+Y
  22         C1=0.5*(AA+BB)
  23         C2=C1-AA
  24         S8=0.0
  25         S16=0.0
  26         DO 1 I=1,4
  27         U=X(I)*C2
  28 1       S8=S8+W(I)*(F(C1+U)+F(C1-U))
  29         DO 3 I=5,12
  30         U=X(I)*C2
  31 3       S16=S16+W(I)*(F(C1+U)+F(C1-U))
  32         S8=S8*C2
  33         S16=S16*C2
  34         IF(ABS(S16-S8).GT.EPS*(1.+ABS(S16))) GOTO 4
  35         GAUSS3=GAUSS3+S16
  36         AA=BB
  37         GOTO 5
  38 4       Y=0.5*Y
  39         IF(ABS(Y).GT.DELTA) GOTO 2
  40         WRITE(6,7)
  41         GAUSS3=0.0
  42         RETURN
  43 7       FORMAT(1X,'GAUSS3....TOO HIGH ACURACY REQUIRED')
  44         END