C QG7 10
C ..................................................................QG7 20
C QG7 30
C SUBROUTINE QG7 QG7 40
C QG7 50
C PURPOSE QG7 60
C TO COMPUTE INTEGRAL(FCT(X), SUMMED OVER X FROM XL TO XU) QG7 70
C QG7 80
C USAGE QG7 90
C CALL QG7 (XL,XU,FCT,Y) QG7 100
C PARAMETER FCT REQUIRES AN EXTERNAL STATEMENT QG7 110
C QG7 120
C DESCRIPTION OF PARAMETERS QG7 130
C XL - THE LOWER BOUND OF THE INTERVAL. QG7 140
C XU - THE UPPER BOUND OF THE INTERVAL. QG7 150
C FCT - THE NAME OF AN EXTERNAL FUNCTION SUBPROGRAM USED. QG7 160
C Y - THE RESULTING INTEGRAL VALUE. QG7 170
C QG7 180
C REMARKS QG7 190
C NONE QG7 200
C QG7 210
C SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED QG7 220
C THE EXTERNAL FUNCTION SUBPROGRAM FCT(X) MUST BE FURNISHED QG7 230
C BY THE USER. QG7 240
C QG7 250
C METHOD QG7 260
C EVALUATION IS DONE BY MEANS OF 7-POINT GAUSS QUADRATURE QG7 270
C FORMULA, WHICH INTEGRATES POLYNOMIALS UP TO DEGREE 13 QG7 280
C EXACTLY. QG7 290
C FOR REFERENCE, SEE QG7 300
C V.I.KRYLOV, APPROXIMATE CALCULATION OF INTEGRALS, QG7 310
C MACMILLAN, NEW YORK/LONDON, 1962, PP.100-111 AND 337-338. QG7 320
C QG7 330
C ..................................................................QG7 340
C QG7 350
SUBROUTINE QG7(XL,XU,FCT,Y) QG7 360
C QG7 370
C QG7 380
A=.5*(XU+XL) QG7 390
B=XU-XL QG7 400
C=.4745540*B QG7 410
Y=.06474248*(FCT(A+C)+FCT(A-C)) QG7 420
C=.3707656*B QG7 430
Y=Y+.1398527*(FCT(A+C)+FCT(A-C)) QG7 440
C=.2029226*B QG7 450
Y=Y+.1909150*(FCT(A+C)+FCT(A-C)) QG7 460
Y=B*(Y+.2089796*FCT(A)) QG7 470
RETURN QG7 480
END QG7 490