C--------------------------------------------------------------------
C Fortran 77 program to test PSI
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 EPS - the smallest positive floating-point
C number such that 1.0+EPS .NE. 1.0
C EPSNEG - the smallest positive floating-point
C number such that 1.0-EPSNEG .NE. 1.0
C
C REN(K) - a function subprogram returning random real
C numbers uniformly distributed over (0,1)
C
C
C Intrinsic Fortran functions required are:
C
C ABS, DBLE, LOG, MAX, REAL, SQRT
C
C Reference: "Performance evaluation of programs related
C to the real gamma function", W. J. Cody,
C submitted for publication.
C
C Latest modification: May 30, 1989
C
C Author: W. J. Cody
C Mathematics and Computer Science Division
C Argonne National Laboratory
C Argonne, IL 60439
C
C--------------------------------------------------------------------
INTEGER I,IBETA,IEXP,IOUT,IRND,IT,J,JT,K1,K2,K3,
1 MACHEP,MAXEXP,MINEXP,N,NDUM,NEGEP,NGRD
CS REAL
CD DOUBLE PRECISION
1 A,AIT,ALBETA,ALL9,B,BETA,CONV,DEL,EIGHT,EPS,
2 EPSNEG,HALF,ONE,ONE7,ONE6,PSI,REN,R6,R7,THREE,
3 TWENTY,Y,V0,W,X,XH,XL,XL2,XMAX,XMIN,XN,XX,X0,
4 X01,X1,Z,ZERO,ZH,ZZ
CS DATA ZERO,ONE,THREE/0.0E0,1.0E0,3.0E0/,
CS 1 HALF,EIGHT,TWENTY,ALL9/0.5E0,8.0E0,20.0E0,-999.0E0/,
CS 2 XL2/6.9314718055994530942E-1/,
CS 3 ONE7,ONE6/-17.625E0,-16.875E0/,
CS 4 X0,X01,V0/374.0E0,256.0E0,-6.7240239024288040437E-04/
CD DATA ZERO,ONE,THREE/0.0E0,1.0E0,3.0E0/,
CD 1 HALF,EIGHT,TWENTY,ALL9/0.5D0,8.0D0,20.0D0,-999.0D0/,
CD 2 XL2/6.9314718055994530942D-1/,
CD 3 ONE7,ONE6/-17.625D0,-16.875D0/,
CD 4 X0,X01,V0/374.0D0,256.0D0,-6.7240239024288040437D-04/
DATA IOUT/6/
C--------------------------------------------------------------------
C Statement functions for conversion between integer and float
C--------------------------------------------------------------------
CS CONV(NDUM) = REAL(NDUM)
CD CONV(NDUM) = DBLE(NDUM)
C--------------------------------------------------------------------
C Determine machine parameters and set constants
C--------------------------------------------------------------------
CALL MACHAR(IBETA,IT,IRND,NGRD,MACHEP,NEGEP,IEXP,MINEXP,
1 MAXEXP,EPS,EPSNEG,XMIN,XMAX)
BETA = CONV(IBETA)
ALBETA = LOG(BETA)
AIT = CONV(IT)
JT = 0
C--------------------------------------------------------------------
C Random argument accuracy tests
C--------------------------------------------------------------------
DO 300 J = 1, 4
K1 = 0
K3 = 0
X1 = ZERO
R6 = ZERO
R7 = ZERO
N = 2000
IF (J .EQ. 1) THEN
A = ZERO
B = ONE
ELSE IF (J .EQ. 2) THEN
A = B + B
B = EIGHT
ELSE IF (J .EQ. 3) THEN
A = B
B = TWENTY
ELSE
A = ONE7
B = ONE6
N = 500
END IF
XN = CONV(N)
DEL = (B - A) / XN
XL = A
DO 200 I = 1, N
X = DEL * REN(JT) + XL
C--------------------------------------------------------------------
C Carefully purify arguments and evaluate identity
C--------------------------------------------------------------------
XX = X * HALF
XH = XX + HALF
XX = XH - HALF
X = XX + XX
Z = PSI(X)
ZH = PSI(XH)
ZZ = PSI(XX)
ZZ = (ZZ+ZH)*HALF + XL2
C--------------------------------------------------------------------
C Accumulate results
C--------------------------------------------------------------------
W = (ZZ - Z) / ZZ
IF (W .GT. ZERO) THEN
K1 = K1 + 1
ELSE IF (W .LT. ZERO) THEN
K3 = K3 + 1
END IF
W = ABS(W)
IF (W .GT. R6) THEN
R6 = W
X1 = X
END IF
R7 = R7 + W * W
XL = XL + DEL
200 CONTINUE
C--------------------------------------------------------------------
C Process and output statistics
C--------------------------------------------------------------------
K2 = N - K3 - K1
R7 = SQRT(R7/XN)
IF (2*(J/2) .NE. J) WRITE (IOUT,1000)
WRITE (IOUT,1001)
WRITE (IOUT,1010) N,A,B
WRITE (IOUT,1011) K1,K2,K3
WRITE (IOUT,1020) IT,IBETA
IF (R6 .NE. ZERO) THEN
W = LOG(ABS(R6))/ALBETA
ELSE
W = ALL9
END IF
WRITE (IOUT,1021) R6,IBETA,W,X1
W = MAX(AIT+W,ZERO)
WRITE (IOUT,1022) IBETA,W
IF (R7 .NE. ZERO) THEN
W = LOG(ABS(R7))/ALBETA
ELSE
W = ALL9
END IF
WRITE (IOUT,1023) R7,IBETA,W
W = MAX(AIT+W,ZERO)
WRITE (IOUT,1022) IBETA,W
300 CONTINUE
C--------------------------------------------------------------------
C Special tests
C--------------------------------------------------------------------
WRITE (IOUT,1030)
X = X0/X01
Y = PSI(X)
Z = (Y-V0)/V0
IF (Z .NE. ZERO) THEN
W = LOG(ABS(Z))/ALBETA
ELSE
W = ALL9
END IF
W = MAX(AIT+W,ZERO)
WRITE (IOUT,1031) X,Y,IBETA,W
WRITE (IOUT,1033)
IF (XMAX*XMIN .GE. ONE) THEN
X = XMIN
ELSE
X = ONE / XMAX
END IF
WRITE (IOUT,1035) X
Y = PSI(X)
WRITE (IOUT,1036) Y
X = XMAX
WRITE (IOUT,1035) X
Y = PSI(X)
WRITE (IOUT,1036) Y
C--------------------------------------------------------------------
C Test of error returns
C--------------------------------------------------------------------
WRITE (IOUT,1037)
X = ZERO
WRITE (IOUT,1034) X
Y = PSI(X)
WRITE (IOUT,1036) Y
X = -THREE/EPS
WRITE (IOUT,1034) X
Y = PSI(X)
WRITE (IOUT,1036) Y
WRITE (IOUT,1100)
STOP
C--------------------------------------------------------------------
1000 FORMAT('1')
1001 FORMAT(' Test of PSI(X) vs (PSI(X/2)+PSI(X/2+1/2))/2 + ln(2)'
1 //)
1010 FORMAT(I7,' random arguments were tested from the interval ',
1 1H(,F5.1,1H,,F5.1,1H)//)
1011 FORMAT(' ABS(PSI(X)) was larger',I6,' times', /
1 21X,' agreed',I6,' times, and'/
1 17X,'was smaller',I6,' times.'//)
1020 FORMAT(' There are',I4,' base',I4,
1 ' significant digits in a floating-point number.' //)
1021 FORMAT(' The maximum relative error of',E15.4,3H = ,I4,3H **,
1 F7.2/4X,'occurred for X =',E13.6)
1022 FORMAT(' The estimated loss of base',I4,
1 ' significant digits is',F7.2//)
1023 FORMAT(' The root mean square relative error was',E15.4,
1 3H = ,I4,3H **,F7.2)
1030 FORMAT('1Special Tests'//)
1031 FORMAT(' Accuracy near positive zero'//' PSI(',E14.7,') = ',
1 E24.17/13X,'Loss of base',I3,' digits = ',F7.2/)
1033 FORMAT(//' Test with extreme arguments'/)
1034 FORMAT(' PSI will be called with the argument ',E17.10/
1 ' This may stop execution.'/)
1035 FORMAT(' PSI will be called with the argument ',E17.10/
1 ' This should not stop execution.'/)
1036 FORMAT(' PSI returned the value',E25.17//)
1037 FORMAT(//' Test of error returns'//)
1100 FORMAT(' This concludes the tests.')
C---------- Last card of PSI test program ----------
END
SUBROUTINE MACHAR(IBETA,IT,IRND,NGRD,MACHEP,NEGEP,IEXP,MINEXP,
1 MAXEXP,EPS,EPSNEG,XMIN,XMAX)
C----------------------------------------------------------------------
C This Fortran 77 subroutine is intended to determine the parameters
C of the floating-point arithmetic system specified below. The
C determination of the first three uses an extension of an algorithm
C due to M. Malcolm, CACM 15 (1972), pp. 949-951, incorporating some,
C but not all, of the improvements suggested by M. Gentleman and S.
C Marovich, CACM 17 (1974), pp. 276-277. An earlier version of this
C program was published in the book Software Manual for the
C Elementary Functions by W. J. Cody and W. Waite, Prentice-Hall,
C Englewood Cliffs, NJ, 1980.
C
C The program as given here must be modified before compiling. If
C a single (double) precision version is desired, change all
C occurrences of CS (CD) in columns 1 and 2 to blanks.
C
C Parameter values reported are as follows:
C
C IBETA - the radix for the floating-point representation
C IT - the number of base IBETA digits in the floating-point
C significand
C IRND - 0 if floating-point addition chops
C 1 if floating-point addition rounds, but not in the
C IEEE style
C 2 if floating-point addition rounds in the IEEE style
C 3 if floating-point addition chops, and there is
C partial underflow
C 4 if floating-point addition rounds, but not in the
C IEEE style, and there is partial underflow
C 5 if floating-point addition rounds in the IEEE style,
C and there is partial underflow
C NGRD - the number of guard digits for multiplication with
C truncating arithmetic. It is
C 0 if floating-point arithmetic rounds, or if it
C truncates and only IT base IBETA digits
C participate in the post-normalization shift of the
C floating-point significand in multiplication;
C 1 if floating-point arithmetic truncates and more
C than IT base IBETA digits participate in the
C post-normalization shift of the floating-point
C significand in multiplication.
C MACHEP - the largest negative integer such that
C 1.0+FLOAT(IBETA)**MACHEP .NE. 1.0, except that
C MACHEP is bounded below by -(IT+3)
C NEGEPS - the largest negative integer such that
C 1.0-FLOAT(IBETA)**NEGEPS .NE. 1.0, except that
C NEGEPS is bounded below by -(IT+3)
C IEXP - the number of bits (decimal places if IBETA = 10)
C reserved for the representation of the exponent
C (including the bias or sign) of a floating-point
C number
C MINEXP - the largest in magnitude negative integer such that
C FLOAT(IBETA)**MINEXP is positive and normalized
C MAXEXP - the smallest positive power of BETA that overflows
C EPS - FLOAT(IBETA)**MACHEP.
C EPSNEG - FLOAT(IBETA)**NEGEPS.
C XMIN - the smallest non-vanishing normalized floating-point
C power of the radix, i.e., XMIN = FLOAT(IBETA)**MINEXP
C XMAX - the largest finite floating-point number. In
C particular XMAX = (1.0-EPSNEG)*FLOAT(IBETA)**MAXEXP
C Note - on some machines XMAX will be only the
C second, or perhaps third, largest number, being
C too small by 1 or 2 units in the last digit of
C the significand.
C
C Latest modification: May 30, 1989
C
C Author: W. J. Cody
C Mathematics and Computer Science Division
C Argonne National Laboratory
C Argonne, IL 60439
C
C----------------------------------------------------------------------
INTEGER I,IBETA,IEXP,IRND,IT,ITEMP,IZ,J,K,MACHEP,MAXEXP,
1 MINEXP,MX,NEGEP,NGRD,NXRES
CS REAL
CD DOUBLE PRECISION
1 A,B,BETA,BETAIN,BETAH,CONV,EPS,EPSNEG,ONE,T,TEMP,TEMPA,
2 TEMP1,TWO,XMAX,XMIN,Y,Z,ZERO
C----------------------------------------------------------------------
CS CONV(I) = REAL(I)
CD CONV(I) = DBLE(I)
ONE = CONV(1)
TWO = ONE + ONE
ZERO = ONE - ONE
C----------------------------------------------------------------------
C Determine IBETA, BETA ala Malcolm.
C----------------------------------------------------------------------
A = ONE
10 A = A + A
TEMP = A+ONE
TEMP1 = TEMP-A
IF (TEMP1-ONE .EQ. ZERO) GO TO 10
B = ONE
20 B = B + B
TEMP = A+B
ITEMP = INT(TEMP-A)
IF (ITEMP .EQ. 0) GO TO 20
IBETA = ITEMP
BETA = CONV(IBETA)
C----------------------------------------------------------------------
C Determine IT, IRND.
C----------------------------------------------------------------------
IT = 0
B = ONE
100 IT = IT + 1
B = B * BETA
TEMP = B+ONE
TEMP1 = TEMP-B
IF (TEMP1-ONE .EQ. ZERO) GO TO 100
IRND = 0
BETAH = BETA / TWO
TEMP = A+BETAH
IF (TEMP-A .NE. ZERO) IRND = 1
TEMPA = A + BETA
TEMP = TEMPA+BETAH
IF ((IRND .EQ. 0) .AND. (TEMP-TEMPA .NE. ZERO)) IRND = 2
C----------------------------------------------------------------------
C Determine NEGEP, EPSNEG.
C----------------------------------------------------------------------
NEGEP = IT + 3
BETAIN = ONE / BETA
A = ONE
DO 200 I = 1, NEGEP
A = A * BETAIN
200 CONTINUE
B = A
210 TEMP = ONE-A
IF (TEMP-ONE .NE. ZERO) GO TO 220
A = A * BETA
NEGEP = NEGEP - 1
GO TO 210
220 NEGEP = -NEGEP
EPSNEG = A
C----------------------------------------------------------------------
C Determine MACHEP, EPS.
C----------------------------------------------------------------------
MACHEP = -IT - 3
A = B
300 TEMP = ONE+A
IF (TEMP-ONE .NE. ZERO) GO TO 320
A = A * BETA
MACHEP = MACHEP + 1
GO TO 300
320 EPS = A
C----------------------------------------------------------------------
C Determine NGRD.
C----------------------------------------------------------------------
NGRD = 0
TEMP = ONE+EPS
IF ((IRND .EQ. 0) .AND. (TEMP*ONE-ONE .NE. ZERO)) NGRD = 1
C----------------------------------------------------------------------
C Determine IEXP, MINEXP, XMIN.
C
C Loop to determine largest I and K = 2**I such that
C (1/BETA) ** (2**(I))
C does not underflow.
C Exit from loop is signaled by an underflow.
C----------------------------------------------------------------------
I = 0
K = 1
Z = BETAIN
T = ONE + EPS
NXRES = 0
400 Y = Z
Z = Y * Y
C----------------------------------------------------------------------
C Check for underflow here.
C----------------------------------------------------------------------
A = Z * ONE
TEMP = Z * T
IF ((A+A .EQ. ZERO) .OR. (ABS(Z) .GE. Y)) GO TO 410
TEMP1 = TEMP * BETAIN
IF (TEMP1*BETA .EQ. Z) GO TO 410
I = I + 1
K = K + K
GO TO 400
410 IF (IBETA .EQ. 10) GO TO 420
IEXP = I + 1
MX = K + K
GO TO 450
C----------------------------------------------------------------------
C This segment is for decimal machines only.
C----------------------------------------------------------------------
420 IEXP = 2
IZ = IBETA
430 IF (K .LT. IZ) GO TO 440
IZ = IZ * IBETA
IEXP = IEXP + 1
GO TO 430
440 MX = IZ + IZ - 1
C----------------------------------------------------------------------
C Loop to determine MINEXP, XMIN.
C Exit from loop is signaled by an underflow.
C----------------------------------------------------------------------
450 XMIN = Y
Y = Y * BETAIN
C----------------------------------------------------------------------
C Check for underflow here.
C----------------------------------------------------------------------
A = Y * ONE
TEMP = Y * T
IF (((A+A) .EQ. ZERO) .OR. (ABS(Y) .GE. XMIN)) GO TO 460
K = K + 1
TEMP1 = TEMP * BETAIN
IF ((TEMP1*BETA .NE. Y) .OR. (TEMP .EQ. Y)) THEN
GO TO 450
ELSE
NXRES = 3
XMIN = Y
END IF
460 MINEXP = -K
C----------------------------------------------------------------------
C Determine MAXEXP, XMAX.
C----------------------------------------------------------------------
IF ((MX .GT. K+K-3) .OR. (IBETA .EQ. 10)) GO TO 500
MX = MX + MX
IEXP = IEXP + 1
500 MAXEXP = MX + MINEXP
C----------------------------------------------------------------------
C Adjust IRND to reflect partial underflow.
C----------------------------------------------------------------------
IRND = IRND + NXRES
C----------------------------------------------------------------------
C Adjust for IEEE-style machines.
C----------------------------------------------------------------------
IF (IRND .GE. 2) MAXEXP = MAXEXP - 2
C----------------------------------------------------------------------
C Adjust for machines with implicit leading bit in binary
C significand, and machines with radix point at extreme
C right of significand.
C----------------------------------------------------------------------
I = MAXEXP + MINEXP
IF ((IBETA .EQ. 2) .AND. (I .EQ. 0)) MAXEXP = MAXEXP - 1
IF (I .GT. 20) MAXEXP = MAXEXP - 1
IF (A .NE. Y) MAXEXP = MAXEXP - 2
XMAX = ONE - EPSNEG
IF (XMAX*ONE .NE. XMAX) XMAX = ONE - BETA * EPSNEG
XMAX = XMAX / (BETA * BETA * BETA * XMIN)
I = MAXEXP + MINEXP + 3
IF (I .LE. 0) GO TO 520
DO 510 J = 1, I
IF (IBETA .EQ. 2) XMAX = XMAX + XMAX
IF (IBETA .NE. 2) XMAX = XMAX * BETA
510 CONTINUE
520 RETURN
C---------- Last line of MACHAR ----------
END
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
C Latest modification: May 30, 1989
C
C Author: W. J. Cody
C Mathematics and Computer Science Division
C Argonne National Laboratory
C Argonne, IL 60439
C
C---------------------------------------------------------------------
INTEGER IY,J,K
CS REAL CONV,C1,C2,C3,ONE,REN
CD DOUBLE PRECISION CONV,C1,C2,C3,ONE,REN
DATA IY/100001/
CS DATA ONE,C1,C2,C3/1.0E0,2796203.0E0,1.0E-6,1.0E-12/
CD DATA ONE,C1,C2,C3/1.0D0,2796203.0D0,1.0D-6,1.0D-12/
C---------------------------------------------------------------------
C Statement functions for conversion between integer and float
C---------------------------------------------------------------------
CS CONV(J) = REAL(J)
CD CONV(J) = DBLE(J)
C---------------------------------------------------------------------
J = K
IY = IY * 125
IY = IY - (IY/2796203) * 2796203
REN = CONV(IY) / C1 * (ONE + C2 + C3)
RETURN
C---------- Last card of REN ----------
END