Trailing-Edge
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PDP-10 Archives
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decuslib20-01
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decus/20-0025/errin.for
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00100 C PROGRAM TO FIND THE INVERSE ERROR FUNCTION
00110 FUNCTION ERRINV(L,C)
00120 DIMENSION Y(7),Y1(14)
00130 IF (L) 1, 110, 1
00140 C CALCULATIONS USING THE ERROR
00150 1 Y(1)=0.
00160 Y(2)=.842700793
00170 Y(3)=.995322265
00180 Y(4)=.999977910
00190 Y(5)=.999999984
00200 Y(6)=1.
00210 Y(7)=1.
00220 IF (C-1.) 10, 20, 20
00230 10 IF (C) 30, 30, 40
00240 20 ERRINV=6.0
00250 GO TO 210
00260 30 ERRINV=0.
00270 GO TO 210
00280 40 DO 50 I=1,7
00290
00300 IF (Y(I)-C) 50, 60, 70
00310 50 CONTINUE
00320 60 ERRINV = I - 1
00330 GO TO 210
00340 70 XC=I-2
00350 DO 90 K=1,20
00360 A=ERR(XC)
00370 TEMP=XC+(C-A)*(.886226925*EXP(XC*XC))
00380 B=ERR(TEMP)
00390 Z=C-B
00400 XC=TEMP
00410 IF (Z-1.E-10) 100, 90, 90
00420 90 CONTINUE
00430 100 ERRINV=TEMP
00440 GO TO 210
00450 110 Y1(1)=1.0
00460 Y1(2)=.157299207E+00
00470 Y1(3)=.467773497E-02
00480 Y1(4)=.220904969E-04
00490 Y1(5)=.154172578E-07
00500 Y1(6)=.153745978E-11
00510 Y1(7)=.215197365E-16
00520 Y1(8)=.418382554E-22
00530 Y1(9)=.112242970E-28
00540 C Y1(10)=.413703172E-36
00550 C Y1(11)=.208848757E-44
00560 C Y1(12)=.144086612E-53
00570 C Y1(13)=.135626115E-63
00580 C Y1(14)=.173955727E-74
00590 IF (1.-C) 120, 120, 130
00600 C CALCULATIONS USING THE COMPLEMENTARY FUNCTION
00610 120 ERRINV=0.
00620 GO TO 210
00630 130 DO 140 I=1,14
00640 IF (Y1(I)-C) 160, 150, 140
00650 140 CONTINUE
00660 XC=12.5
00670 GO TO 170
00680 150 ERRINV = I - 1
00690 GO TO 210
00700 160 XC=I-2
00710 170 DO 190 K=1,30
00720 IF (XC) 180, 175, 180
00730 175 A1=1.0
00740 GO TO 181
00750 180 A1=ERR(-XC)
00760 181 F=XC+(C-A1)*(-0.886226925*EXP(XC*XC))
00770 IF (F) 183, 182, 183
00780 182 B1=1.
00790 GO TO 184
00800 183 B1=ERR(-F)
00810 184 XC=F
00820 Z=ABS((B1-C)/C)
00830 IF (Z-1.E-10) 200, 190, 190
00840 190 CONTINUE
00850 200 ERRINV=F
00860 210 RETURN
00870 END