C QG6 10
C ..................................................................QG6 20
C QG6 30
C SUBROUTINE QG6 QG6 40
C QG6 50
C PURPOSE QG6 60
C TO COMPUTE INTEGRAL(FCT(X), SUMMED OVER X FROM XL TO XU) QG6 70
C QG6 80
C USAGE QG6 90
C CALL QG6 (XL,XU,FCT,Y) QG6 100
C PARAMETER FCT REQUIRES AN EXTERNAL STATEMENT QG6 110
C QG6 120
C DESCRIPTION OF PARAMETERS QG6 130
C XL - THE LOWER BOUND OF THE INTERVAL. QG6 140
C XU - THE UPPER BOUND OF THE INTERVAL. QG6 150
C FCT - THE NAME OF AN EXTERNAL FUNCTION SUBPROGRAM USED. QG6 160
C Y - THE RESULTING INTEGRAL VALUE. QG6 170
C QG6 180
C REMARKS QG6 190
C NONE QG6 200
C QG6 210
C SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED QG6 220
C THE EXTERNAL FUNCTION SUBPROGRAM FCT(X) MUST BE FURNISHED QG6 230
C BY THE USER. QG6 240
C QG6 250
C METHOD QG6 260
C EVALUATION IS DONE BY MEANS OF 6-POINT GAUSS QUADRATURE QG6 270
C FORMULA, WHICH INTEGRATES POLYNOMIALS UP TO DEGREE 11 QG6 280
C EXACTLY. QG6 290
C FOR REFERENCE, SEE QG6 300
C V.I.KRYLOV, APPROXIMATE CALCULATION OF INTEGRALS, QG6 310
C MACMILLAN, NEW YORK/LONDON, 1962, PP.100-111 AND 337-338. QG6 320
C QG6 330
C ..................................................................QG6 340
C QG6 350
SUBROUTINE QG6(XL,XU,FCT,Y) QG6 360
C QG6 370
C QG6 380
A=.5*(XU+XL) QG6 390
B=XU-XL QG6 400
C=.4662348*B QG6 410
Y=.08566225*(FCT(A+C)+FCT(A-C)) QG6 420
C=.3306047*B QG6 430
Y=Y+.1803808*(FCT(A+C)+FCT(A-C)) QG6 440
C=.1193096*B QG6 450
Y=B*(Y+.2339570*(FCT(A+C)+FCT(A-C))) QG6 460
RETURN QG6 470
END QG6 480