DOUBLE PRECISION FUNCTION D1MACH(I) INTEGER I C C DOUBLE-PRECISION MACHINE CONSTANTS C D1MACH( 1) = B**(EMIN-1), THE SMALLEST POSITIVE MAGNITUDE. C D1MACH( 2) = B**EMAX*(1 - B**(-T)), THE LARGEST MAGNITUDE. C D1MACH( 3) = B**(-T), THE SMALLEST RELATIVE SPACING. C D1MACH( 4) = B**(1-T), THE LARGEST RELATIVE SPACING. C D1MACH( 5) = LOG10(B) C C THIS VERSION ADAPTS AUTOMATICALLY TO MOST CURRENT MACHINES. C R1MACH CAN HANDLE AUTO-DOUBLE COMPILING, BUT THIS VERSION OF C D1MACH DOES NOT, BECAUSE WE DO NOT HAVE QUAD CONSTANTS FOR C MANY MACHINES YET. C TO ALTER FOR A PARTICULAR ENVIRONMENT, THE DESIRED SET OF DATA C STATEMENTS MAY BE ACTIVATED BY REMOVING THE C FROM COLUMN 1. C CONSTANTS FOR OLDER MACHINES CAN BE OBTAINED BY C mail netlib@research.bell-labs.com C send old1mach from blas C PLEASE SEND CORRECTIONS TO dmg OR ehg@bell-labs.com. C INTEGER SMALL(2) INTEGER LARGE(2) INTEGER RIGHT(2) INTEGER DIVER(2) INTEGER LOG10(2) INTEGER SC, CRAY1(38), J COMMON /D9MACH/ CRAY1 SAVE SMALL, LARGE, RIGHT, DIVER, LOG10, SC DOUBLE PRECISION DMACH(5) EQUIVALENCE (DMACH(1),SMALL(1)) EQUIVALENCE (DMACH(2),LARGE(1)) EQUIVALENCE (DMACH(3),RIGHT(1)) EQUIVALENCE (DMACH(4),DIVER(1)) EQUIVALENCE (DMACH(5),LOG10(1)) C C MACHINE CONSTANTS FOR THE HONEYWELL DPS 8/70 SERIES. C DATA SMALL(1),SMALL(2) / O402400000000, O000000000000 / C DATA LARGE(1),LARGE(2) / O376777777777, O777777777777 / C DATA RIGHT(1),RIGHT(2) / O604400000000, O000000000000 / C DATA DIVER(1),DIVER(2) / O606400000000, O000000000000 / C DATA LOG10(1),LOG10(2) / O776464202324, O117571775714 /, SC/987/ C C MACHINE CONSTANTS FOR PDP-11 FORTRANS SUPPORTING C 32-BIT INTEGERS. C DATA SMALL(1),SMALL(2) / 8388608, 0 / C DATA LARGE(1),LARGE(2) / 2147483647, -1 / C DATA RIGHT(1),RIGHT(2) / 612368384, 0 / C DATA DIVER(1),DIVER(2) / 620756992, 0 / C DATA LOG10(1),LOG10(2) / 1067065498, -2063872008 /, SC/987/ C C MACHINE CONSTANTS FOR THE SEQUENT BALANCE 8000 C DATA SMALL(1),SMALL(2) / $00000000, $00100000 / C DATA LARGE(1),LARGE(2) / $FFFFFFFF, $7FEFFFFF / C DATA RIGHT(1),RIGHT(2) / $00000000, $3CA00000 / C DATA DIVER(1),DIVER(2) / $00000000, $3CB00000 / C DATA LOG10(1),LOG10(2) / $509F79FF, $3FD34413 /, SC/987/ C C MACHINE CONSTANTS FOR THE UNIVAC 1100 SERIES. C DATA SMALL(1),SMALL(2) / O000040000000, O000000000000 / C DATA LARGE(1),LARGE(2) / O377777777777, O777777777777 / C DATA RIGHT(1),RIGHT(2) / O170540000000, O000000000000 / C DATA DIVER(1),DIVER(2) / O170640000000, O000000000000 / C DATA LOG10(1),LOG10(2) / O177746420232, O411757177572 /, SC/987/ C C ON FIRST CALL, IF NO DATA UNCOMMENTED, TEST MACHINE TYPES. IF (SC .NE. 987) THEN DMACH(1) = 1.D13 IF ( SMALL(1) .EQ. 1117925532 * .AND. SMALL(2) .EQ. -448790528) THEN * *** IEEE BIG ENDIAN *** SMALL(1) = 1048576 SMALL(2) = 0 LARGE(1) = 2146435071 LARGE(2) = -1 RIGHT(1) = 1017118720 RIGHT(2) = 0 DIVER(1) = 1018167296 DIVER(2) = 0 LOG10(1) = 1070810131 LOG10(2) = 1352628735 ELSE IF ( SMALL(2) .EQ. 1117925532 * .AND. SMALL(1) .EQ. -448790528) THEN * *** IEEE LITTLE ENDIAN *** SMALL(2) = 1048576 SMALL(1) = 0 LARGE(2) = 2146435071 LARGE(1) = -1 RIGHT(2) = 1017118720 RIGHT(1) = 0 DIVER(2) = 1018167296 DIVER(1) = 0 LOG10(2) = 1070810131 LOG10(1) = 1352628735 ELSE IF ( SMALL(1) .EQ. -2065213935 * .AND. SMALL(2) .EQ. 10752) THEN * *** VAX WITH D_FLOATING *** SMALL(1) = 128 SMALL(2) = 0 LARGE(1) = -32769 LARGE(2) = -1 RIGHT(1) = 9344 RIGHT(2) = 0 DIVER(1) = 9472 DIVER(2) = 0 LOG10(1) = 546979738 LOG10(2) = -805796613 ELSE IF ( SMALL(1) .EQ. 1267827943 * .AND. SMALL(2) .EQ. 704643072) THEN * *** IBM MAINFRAME *** SMALL(1) = 1048576 SMALL(2) = 0 LARGE(1) = 2147483647 LARGE(2) = -1 RIGHT(1) = 856686592 RIGHT(2) = 0 DIVER(1) = 873463808 DIVER(2) = 0 LOG10(1) = 1091781651 LOG10(2) = 1352628735 ELSE IF ( SMALL(1) .EQ. 1120022684 * .AND. SMALL(2) .EQ. -448790528) THEN * *** CONVEX C-1 *** SMALL(1) = 1048576 SMALL(2) = 0 LARGE(1) = 2147483647 LARGE(2) = -1 RIGHT(1) = 1019215872 RIGHT(2) = 0 DIVER(1) = 1020264448 DIVER(2) = 0 LOG10(1) = 1072907283 LOG10(2) = 1352628735 ELSE IF ( SMALL(1) .EQ. 815547074 * .AND. SMALL(2) .EQ. 58688) THEN * *** VAX G-FLOATING *** SMALL(1) = 16 SMALL(2) = 0 LARGE(1) = -32769 LARGE(2) = -1 RIGHT(1) = 15552 RIGHT(2) = 0 DIVER(1) = 15568 DIVER(2) = 0 LOG10(1) = 1142112243 LOG10(2) = 2046775455 ELSE DMACH(2) = 1.D27 + 1 DMACH(3) = 1.D27 LARGE(2) = LARGE(2) - RIGHT(2) IF (LARGE(2) .EQ. 64 .AND. SMALL(2) .EQ. 0) THEN CRAY1(1) = 67291416 DO 10 J = 1, 20 10 CRAY1(J+1) = CRAY1(J) + CRAY1(J) CRAY1(22) = CRAY1(21) + 321322 DO 20 J = 22, 37 20 CRAY1(J+1) = CRAY1(J) + CRAY1(J) IF (CRAY1(38) .EQ. SMALL(1)) THEN * *** CRAY *** c SMALL(1) = 2332160919536140288.D0 SMALL(2) = 0 c LARGE(1) = 6917247552664371199.D0 c LARGE(2) = 281474976710654.D0 c RIGHT(1) = 4585649583081652224.D0 RIGHT(2) = 0 c DIVER(1) = 4585931058058362880.D0 DIVER(2) = 0 c LOG10(1) = 4611574008272714703.D0 c LOG10(2) = 272234615232940.D0 ELSE WRITE(*,9000) STOP 779 END IF ELSE WRITE(*,9000) STOP 779 END IF END IF SC = 987 END IF * SANITY CHECK IF (DMACH(4) .GE. 1.0D0) STOP 778 IF (I .LT. 1 .OR. I .GT. 5) THEN WRITE(*,*) 'D1MACH(I): I =',I,' is out of bounds.' STOP END IF D1MACH = DMACH(I) RETURN 9000 FORMAT(/' Adjust D1MACH by uncommenting data statements'/ *' appropriate for your machine.') * /* ANSI C source for D1MACH -- remove the * in column 1 */ *#include *#include *#include *double d1mach_(long *i) *{ * switch(*i){ * case 1: return DBL_MIN; * case 2: return DBL_MAX; * case 3: return DBL_EPSILON/FLT_RADIX; * case 4: return DBL_EPSILON; * case 5: return log10(FLT_RADIX); * } * fprintf(stderr, "invalid argument: d1mach(%ld)\n", *i); * exit(1); return 0; /* for compilers that complain of missing return values */ *} END