C PROGRAM TO TEST TANH C C DATA REQUIRED C C NONE C C SUBPROGRAMS REQUIRED FROM THIS PACKAGE C C MACHAR - AN ENVIRONMENTAL INQUIRY PROGRAM PROVIDING C INFORMATION ON THE FLOATING-POINT ARITHMETIC C SYSTEM. NOTE THAT THE CALL TO MACHAR CAN C BE DELETED PROVIDED THE FOLLOWING FIVE C PARAMETERS ARE ASSIGNED THE VALUES INDICATED C C IBETA - THE RADIX OF THE FLOATING-POINT SYSTEM C IT - THE NUMBER OF BASE-IBETA DIGITS IN THE C SIGNIFICAND OF A FLOATING-POINT NUMBER C MINEXP - THE LARGEST IN MAGNITUDE NEGATIVE C INTEGER SUCH THAT FLOAT(IBETA)**MINEXP C IS A POSITIVE FLOATING-POINT NUMBER C XMIN - THE SMALLEST NON-VANISHING FLOATING-POINT C POWER OF THE RADIX C XMAX - THE LARGEST FINITE FLOATING-POINT NO. C C REN(K) - A FUNCTION SUBPROGRAM RETURNING RANDOM REAL C NUMBERS UNIFORMLY DISTRIBUTED OVER (0,1) C C C STANDARD FORTRAN SUBPROGRAMS REQUIRED C C ABS, ALOG, AMAX1, FLOAT, SQRT, TANH C C C LATEST REVISION - DECEMBER 6, 1979 C C AUTHOR - W. J. CODY C ARGONNE NATIONAL LABORATORY C C INTEGER I,IBETA,IEXP,IOUT,IRND,IT,I1,J,K1,K2,K3,MACHEP, 1 MAXEXP,MINEXP,N,NEGEP,NGRD REAL A,AIT,ALBETA,B,BETA,BETAP,C,D,DEL,EPS,EPSNEG,EXPON,HALF, 1 ONE,RAN,R6,R7,W,X,XL,XMAX,XMIN,XN,X1,Y,Z,ZERO,ZZ C IOUT = 6 CALL MACHAR(IBETA,IT,IRND,NGRD,MACHEP,NEGEP,IEXP,MINEXP, 1 MAXEXP,EPS,EPSNEG,XMIN,XMAX) BETA = FLOAT(IBETA) ALBETA = ALOG(BETA) AIT = FLOAT(IT) ZERO = 0.0E0 ONE = 1.0E0 HALF = 0.5E0 A = 0.125E0 B = ALOG(3.0E0) * HALF C = 1.2435300177159620805E-1 D = ALOG(2.0E0) + (AIT+ONE) * ALOG(BETA) * HALF N = 2000 XN = FLOAT(N) I1 = 0 C----------------------------------------------------------------- C RANDOM ARGUMENT ACCURACY TESTS C----------------------------------------------------------------- DO 300 J = 1, 2 K1 = 0 K3 = 0 X1 = ZERO R6 = ZERO R7 = ZERO DEL = (B - A) / XN XL = A C DO 200 I = 1, N X = DEL * REN(I1) + XL Z = TANH(X) Y = X - 0.125E0 ZZ = TANH(Y) ZZ = (ZZ + C) / (ONE + C*ZZ) W = ONE IF (Z .NE. ZERO) W = (Z - ZZ) / Z IF (W .GT. ZERO) K1 = K1 + 1 IF (W .LT. ZERO) K3 = K3 + 1 W = ABS(W) IF (W .LE. R6) GO TO 120 R6 = W X1 = X 120 R7 = R7 + W * W XL = XL + DEL 200 CONTINUE C K2 = N - K3 - K1 R7 = SQRT(R7/XN) WRITE (IOUT,1000) WRITE (IOUT,1010) N,A,B WRITE (IOUT,1011) K1,K2,K3 WRITE (IOUT,1020) IT,IBETA W = -999.0E0 IF (R6 .NE. ZERO) W = ALOG(ABS(R6))/ALBETA WRITE (IOUT,1021) R6,IBETA,W,X1 W = AMAX1(AIT+W,ZERO) WRITE (IOUT,1022) IBETA,W W = -999.0E0 IF (R7 .NE. ZERO) W = ALOG(ABS(R7))/ALBETA WRITE (IOUT,1023) R7,IBETA,W W = AMAX1(AIT+W,ZERO) WRITE (IOUT,1022) IBETA,W A = B + A B = D 300 CONTINUE C----------------------------------------------------------------- C SPECIAL TESTS C----------------------------------------------------------------- WRITE (IOUT,1025) WRITE (IOUT,1030) C DO 320 I = 1, 5 X = REN(I1) Z = TANH(X) + TANH(-X) WRITE (IOUT,1060) X, Z 320 CONTINUE C WRITE (IOUT,1031) BETAP = BETA ** IT X = REN(I1) / BETAP C DO 330 I = 1, 5 Z = X - TANH(X) WRITE (IOUT,1060) X, Z X = X / BETA 330 CONTINUE C WRITE (IOUT,1032) X = D B = 4.0E0 C DO 340 I = 1, 5 Z = (TANH(X) - HALF) - HALF WRITE (IOUT,1060) X, Z X = X + B 340 CONTINUE C WRITE (IOUT,1035) EXPON = FLOAT(MINEXP) * 0.75E0 X = BETA ** EXPON Z = TANH(X) WRITE (IOUT,1061) X, Z WRITE (IOUT,1040) XMAX Z = TANH(XMAX) WRITE (IOUT,1061) XMAX, Z WRITE (IOUT,1040) XMIN Z = TANH(XMIN) WRITE (IOUT,1061) XMIN, Z X = ZERO WRITE (IOUT,1040) X Z = TANH(X) WRITE (IOUT,1061) X, Z WRITE (IOUT,1100) STOP 1000 FORMAT(20H1TEST OF TANH(X) VS , 1 50H(TANH(X-1/8)+TANH(1/8))/(1+TANH(X-1/8)TANH(1/8)) //) 1010 FORMAT(I7,47H RANDOM ARGUMENTS WERE TESTED FROM THE INTERVAL / 1 6X,1H(,E15.4,1H,,E15.4,1H)//) 1011 FORMAT(19H TANH(X) WAS LARGER,I6,7H TIMES, / 1 12X,7H AGREED,I6,11H TIMES, AND / 2 8X,11HWAS SMALLER,I6,7H TIMES.//) 1020 FORMAT(10H THERE ARE,I4,5H BASE,I4, 1 46H SIGNIFICANT DIGITS IN A FLOATING-POINT NUMBER //) 1021 FORMAT(30H THE MAXIMUM RELATIVE ERROR OF,E15.4,3H = ,I4,3H **, 1 F7.2/4X,16HOCCURRED FOR X =,E17.6) 1022 FORMAT(27H THE ESTIMATED LOSS OF BASE,I4, 1 22H SIGNIFICANT DIGITS IS,F7.2//) 1023 FORMAT(40H THE ROOT MEAN SQUARE RELATIVE ERROR WAS,E15.4, 1 3H = ,I4,3H **,F7.2) 1025 FORMAT(14H1SPECIAL TESTS//) 1030 FORMAT(53H THE IDENTITY TANH(-X) = -TANH(X) WILL BE TESTED.// 1 8X,1HX,9X,12HF(X) + F(-X)/) 1031 FORMAT(52H THE IDENTITY TANH(X) = X , X SMALL, WILL BE TESTED.// 1 8X,1HX,9X,8HX - F(X)/) 1032 FORMAT(52H THE IDENTITY TANH(X) = 1 , X LARGE, WILL BE TESTED.// 1 8X,1HX,9X,8H1 - F(X)/) 1035 FORMAT(43H TEST OF UNDERFLOW FOR VERY SMALL ARGUMENT. /) 1040 FORMAT(51H THE FUNCTION TANH WILL BE CALLED WITH THE ARGUMENT, 1 E15.7) 1060 FORMAT(2E15.7/) 1061 FORMAT(6X,6H TANH(,E13.6,3H) =,E13.6/) 1100 FORMAT(25H THIS CONCLUDES THE TESTS ) C ---------- LAST CARD OF TANH TEST PROGRAM ---------- END REAL FUNCTION REN(K) C C RANDOM NUMBER GENERATOR - BASED ON ALGORITHM 266 BY PIKE AND C HILL (MODIFIED BY HANSSON), COMMUNICATIONS OF THE ACM, C VOL. 8, NO. 10, OCTOBER 1965. C C THIS SUBPROGRAM IS INTENDED FOR USE ON COMPUTERS WITH C FIXED POINT WORDLENGTH OF AT LEAST 29 BITS. IT IS C BEST IF THE FLOATING POINT SIGNIFICAND HAS AT MOST C 29 BITS. C INTEGER IY,J,K DATA IY/100001/ C J = K IY = IY * 125 IY = IY - (IY/2796203) * 2796203 REN = FLOAT(IY) / 2796203.0E0 RETURN C ---------- LAST CARD OF RAN ---------- END