#include #include "f2c.h" /* If config.h is available, we only need dlamc3 */ #ifndef HAVE_CONFIG doublereal dlamch_(char *cmach) { /* -- LAPACK auxiliary routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University October 31, 1992 Purpose ======= DLAMCH determines double precision machine parameters. Arguments ========= CMACH (input) CHARACTER*1 Specifies the value to be returned by DLAMCH: = 'E' or 'e', DLAMCH := eps = 'S' or 's , DLAMCH := sfmin = 'B' or 'b', DLAMCH := base = 'P' or 'p', DLAMCH := eps*base = 'N' or 'n', DLAMCH := t = 'R' or 'r', DLAMCH := rnd = 'M' or 'm', DLAMCH := emin = 'U' or 'u', DLAMCH := rmin = 'L' or 'l', DLAMCH := emax = 'O' or 'o', DLAMCH := rmax where eps = relative machine precision sfmin = safe minimum, such that 1/sfmin does not overflow base = base of the machine prec = eps*base t = number of (base) digits in the mantissa rnd = 1.0 when rounding occurs in addition, 0.0 otherwise emin = minimum exponent before (gradual) underflow rmin = underflow threshold - base**(emin-1) emax = largest exponent before overflow rmax = overflow threshold - (base**emax)*(1-eps) ===================================================================== */ /* >>Start of File<< Initialized data */ static logical first = TRUE_; /* System generated locals */ integer i__1; doublereal ret_val; /* Builtin functions */ double pow_di(doublereal *, integer *); /* Local variables */ static doublereal base; static integer beta; static doublereal emin, prec, emax; static integer imin, imax; static logical lrnd; static doublereal rmin, rmax, t, rmach; extern logical lsame_(char *, char *); static doublereal small, sfmin; extern /* Subroutine */ int dlamc2_(integer *, integer *, logical *, doublereal *, integer *, doublereal *, integer *, doublereal *); static integer it; static doublereal rnd, eps; if (first) { first = FALSE_; dlamc2_(&beta, &it, &lrnd, &eps, &imin, &rmin, &imax, &rmax); base = (doublereal) beta; t = (doublereal) it; if (lrnd) { rnd = 1.; i__1 = 1 - it; eps = pow_di(&base, &i__1) / 2; } else { rnd = 0.; i__1 = 1 - it; eps = pow_di(&base, &i__1); } prec = eps * base; emin = (doublereal) imin; emax = (doublereal) imax; sfmin = rmin; small = 1. / rmax; if (small >= sfmin) { /* Use SMALL plus a bit, to avoid the possibility of rou nding causing overflow when computing 1/sfmin. */ sfmin = small * (eps + 1.); } } if (lsame_(cmach, "E")) { rmach = eps; } else if (lsame_(cmach, "S")) { rmach = sfmin; } else if (lsame_(cmach, "B")) { rmach = base; } else if (lsame_(cmach, "P")) { rmach = prec; } else if (lsame_(cmach, "N")) { rmach = t; } else if (lsame_(cmach, "R")) { rmach = rnd; } else if (lsame_(cmach, "M")) { rmach = emin; } else if (lsame_(cmach, "U")) { rmach = rmin; } else if (lsame_(cmach, "L")) { rmach = emax; } else if (lsame_(cmach, "O")) { rmach = rmax; } ret_val = rmach; return ret_val; /* End of DLAMCH */ } /* dlamch_ */ /* Subroutine */ int dlamc1_(integer *beta, integer *t, logical *rnd, logical *ieee1) { /* -- LAPACK auxiliary routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University October 31, 1992 Purpose ======= DLAMC1 determines the machine parameters given by BETA, T, RND, and IEEE1. Arguments ========= BETA (output) INTEGER The base of the machine. T (output) INTEGER The number of ( BETA ) digits in the mantissa. RND (output) LOGICAL Specifies whether proper rounding ( RND = .TRUE. ) or chopping ( RND = .FALSE. ) occurs in addition. This may not be a reliable guide to the way in which the machine performs its arithmetic. IEEE1 (output) LOGICAL Specifies whether rounding appears to be done in the IEEE 'round to nearest' style. Further Details =============== The routine is based on the routine ENVRON by Malcolm and incorporates suggestions by Gentleman and Marovich. See Malcolm M. A. (1972) Algorithms to reveal properties of floating-point arithmetic. Comms. of the ACM, 15, 949-951. Gentleman W. M. and Marovich S. B. (1974) More on algorithms that reveal properties of floating point arithmetic units. Comms. of the ACM, 17, 276-277. ===================================================================== */ /* Initialized data */ static logical first = TRUE_; /* System generated locals */ doublereal d__1, d__2; /* Local variables */ static logical lrnd; static doublereal a, b, c, f; static integer lbeta; static doublereal savec; extern doublereal dlamc3_(doublereal *, doublereal *); static logical lieee1; static doublereal t1, t2; static integer lt; static doublereal one, qtr; if (first) { first = FALSE_; one = 1.; /* LBETA, LIEEE1, LT and LRND are the local values of BE TA, IEEE1, T and RND. Throughout this routine we use the function DLAMC3 to ens ure that relevant values are stored and not held in registers, or are not affected by optimizers. Compute a = 2.0**m with the smallest positive integer m s uch that fl( a + 1.0 ) = a. */ a = 1.; c = 1.; /* + WHILE( C.EQ.ONE )LOOP */ L10: if (c == one) { a *= 2; c = dlamc3_(&a, &one); d__1 = -a; c = dlamc3_(&c, &d__1); goto L10; } /* + END WHILE Now compute b = 2.0**m with the smallest positive integer m such that fl( a + b ) .gt. a. */ b = 1.; c = dlamc3_(&a, &b); /* + WHILE( C.EQ.A )LOOP */ L20: if (c == a) { b *= 2; c = dlamc3_(&a, &b); goto L20; } /* + END WHILE Now compute the base. a and c are neighbouring floating po int numbers in the interval ( beta**t, beta**( t + 1 ) ) and so their difference is beta. Adding 0.25 to c is to ensure that it is truncated to beta and not ( beta - 1 ). */ qtr = one / 4; savec = c; d__1 = -a; c = dlamc3_(&c, &d__1); lbeta = (integer) (c + qtr); /* Now determine whether rounding or chopping occurs, by addin g a bit less than beta/2 and a bit more than beta/2 to a. */ b = (doublereal) lbeta; d__1 = b / 2; d__2 = -b / 100; f = dlamc3_(&d__1, &d__2); c = dlamc3_(&f, &a); if (c == a) { lrnd = TRUE_; } else { lrnd = FALSE_; } d__1 = b / 2; d__2 = b / 100; f = dlamc3_(&d__1, &d__2); c = dlamc3_(&f, &a); if (lrnd && c == a) { lrnd = FALSE_; } /* Try and decide whether rounding is done in the IEEE 'round to nearest' style. B/2 is half a unit in the last place of the two numbers A and SAVEC. Furthermore, A is even, i.e. has last bit zero, and SAVEC is odd. Thus adding B/2 to A should not cha nge A, but adding B/2 to SAVEC should change SAVEC. */ d__1 = b / 2; t1 = dlamc3_(&d__1, &a); d__1 = b / 2; t2 = dlamc3_(&d__1, &savec); lieee1 = t1 == a && t2 > savec && lrnd; /* Now find the mantissa, t. It should be the integer part of log to the base beta of a, however it is safer to determine t by powering. So we find t as the smallest positive integer for which fl( beta**t + 1.0 ) = 1.0. */ lt = 0; a = 1.; c = 1.; /* + WHILE( C.EQ.ONE )LOOP */ L30: if (c == one) { ++lt; a *= lbeta; c = dlamc3_(&a, &one); d__1 = -a; c = dlamc3_(&c, &d__1); goto L30; } /* + END WHILE */ } *beta = lbeta; *t = lt; *rnd = lrnd; *ieee1 = lieee1; return 0; /* End of DLAMC1 */ } /* dlamc1_ */ /* Subroutine */ int dlamc2_(integer *beta, integer *t, logical *rnd, doublereal *eps, integer *emin, doublereal *rmin, integer *emax, doublereal *rmax) { /* -- LAPACK auxiliary routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University October 31, 1992 Purpose ======= DLAMC2 determines the machine parameters specified in its argument list. Arguments ========= BETA (output) INTEGER The base of the machine. T (output) INTEGER The number of ( BETA ) digits in the mantissa. RND (output) LOGICAL Specifies whether proper rounding ( RND = .TRUE. ) or chopping ( RND = .FALSE. ) occurs in addition. This may not be a reliable guide to the way in which the machine performs its arithmetic. EPS (output) DOUBLE PRECISION The smallest positive number such that fl( 1.0 - EPS ) .LT. 1.0, where fl denotes the computed value. EMIN (output) INTEGER The minimum exponent before (gradual) underflow occurs. RMIN (output) DOUBLE PRECISION The smallest normalized number for the machine, given by BASE**( EMIN - 1 ), where BASE is the floating point value of BETA. EMAX (output) INTEGER The maximum exponent before overflow occurs. RMAX (output) DOUBLE PRECISION The largest positive number for the machine, given by BASE**EMAX * ( 1 - EPS ), where BASE is the floating point value of BETA. Further Details =============== The computation of EPS is based on a routine PARANOIA by W. Kahan of the University of California at Berkeley. ===================================================================== */ /* Initialized data */ static logical first = TRUE_; static logical iwarn = FALSE_; /* System generated locals */ integer i__1; doublereal d__1, d__2, d__3, d__4, d__5; /* Builtin functions */ double pow_di(doublereal *, integer *); /* Local variables */ static logical ieee; static doublereal half; static logical lrnd; static doublereal leps, zero, a, b, c; static integer i, lbeta; static doublereal rbase; static integer lemin, lemax, gnmin; static doublereal small; static integer gpmin; static doublereal third, lrmin, lrmax, sixth; extern /* Subroutine */ int dlamc1_(integer *, integer *, logical *, logical *); extern doublereal dlamc3_(doublereal *, doublereal *); static logical lieee1; extern /* Subroutine */ int dlamc4_(integer *, doublereal *, integer *), dlamc5_(integer *, integer *, integer *, logical *, integer *, doublereal *); static integer lt, ngnmin, ngpmin; static doublereal one, two; if (first) { first = FALSE_; zero = 0.; one = 1.; two = 2.; /* LBETA, LT, LRND, LEPS, LEMIN and LRMIN are the local values of BETA, T, RND, EPS, EMIN and RMIN. Throughout this routine we use the function DLAMC3 to ens ure that relevant values are stored and not held in registers, or are not affected by optimizers. DLAMC1 returns the parameters LBETA, LT, LRND and LIEEE1. */ dlamc1_(&lbeta, <, &lrnd, &lieee1); /* Start to find EPS. */ b = (doublereal) lbeta; i__1 = -lt; a = pow_di(&b, &i__1); leps = a; /* Try some tricks to see whether or not this is the correct E PS. */ b = two / 3; half = one / 2; d__1 = -half; sixth = dlamc3_(&b, &d__1); third = dlamc3_(&sixth, &sixth); d__1 = -half; b = dlamc3_(&third, &d__1); b = dlamc3_(&b, &sixth); b = abs(b); if (b < leps) { b = leps; } leps = 1.; /* + WHILE( ( LEPS.GT.B ).AND.( B.GT.ZERO ) )LOOP */ L10: if (leps > b && b > zero) { leps = b; d__1 = half * leps; /* Computing 5th power */ d__3 = two, d__4 = d__3, d__3 *= d__3; /* Computing 2nd power */ d__5 = leps; d__2 = d__4 * (d__3 * d__3) * (d__5 * d__5); c = dlamc3_(&d__1, &d__2); d__1 = -c; c = dlamc3_(&half, &d__1); b = dlamc3_(&half, &c); d__1 = -b; c = dlamc3_(&half, &d__1); b = dlamc3_(&half, &c); goto L10; } /* + END WHILE */ if (a < leps) { leps = a; } /* Computation of EPS complete. Now find EMIN. Let A = + or - 1, and + or - (1 + BASE**(-3 )). Keep dividing A by BETA until (gradual) underflow occurs. T his is detected when we cannot recover the previous A. */ rbase = one / lbeta; small = one; for (i = 1; i <= 3; ++i) { d__1 = small * rbase; small = dlamc3_(&d__1, &zero); /* L20: */ } a = dlamc3_(&one, &small); dlamc4_(&ngpmin, &one, &lbeta); d__1 = -one; dlamc4_(&ngnmin, &d__1, &lbeta); dlamc4_(&gpmin, &a, &lbeta); d__1 = -a; dlamc4_(&gnmin, &d__1, &lbeta); ieee = FALSE_; if (ngpmin == ngnmin && gpmin == gnmin) { if (ngpmin == gpmin) { lemin = ngpmin; /* ( Non twos-complement machines, no gradual under flow; e.g., VAX ) */ } else if (gpmin - ngpmin == 3) { lemin = ngpmin - 1 + lt; ieee = TRUE_; /* ( Non twos-complement machines, with gradual und erflow; e.g., IEEE standard followers ) */ } else { lemin = min(ngpmin,gpmin); /* ( A guess; no known machine ) */ iwarn = TRUE_; } } else if (ngpmin == gpmin && ngnmin == gnmin) { if ((i__1 = ngpmin - ngnmin, abs(i__1)) == 1) { lemin = max(ngpmin,ngnmin); /* ( Twos-complement machines, no gradual underflow ; e.g., CYBER 205 ) */ } else { lemin = min(ngpmin,ngnmin); /* ( A guess; no known machine ) */ iwarn = TRUE_; } } else if ((i__1 = ngpmin - ngnmin, abs(i__1)) == 1 && gpmin == gnmin) { if (gpmin - min(ngpmin,ngnmin) == 3) { lemin = max(ngpmin,ngnmin) - 1 + lt; /* ( Twos-complement machines with gradual underflo w; no known machine ) */ } else { lemin = min(ngpmin,ngnmin); /* ( A guess; no known machine ) */ iwarn = TRUE_; } } else { /* Computing MIN */ i__1 = min(ngpmin,ngnmin), i__1 = min(i__1,gpmin); lemin = min(i__1,gnmin); /* ( A guess; no known machine ) */ iwarn = TRUE_; } /* ** Comment out this if block if EMIN is ok */ if (iwarn) { first = TRUE_; printf("\n\n WARNING. The value EMIN may be incorrect:- "); printf("EMIN = %8i\n",lemin); printf("If, after inspection, the value EMIN looks acceptable"); printf("please comment out \n the IF block as marked within the"); printf("code of routine DLAMC2, \n otherwise supply EMIN"); printf("explicitly.\n"); } /* ** Assume IEEE arithmetic if we found denormalised numbers abo ve, or if arithmetic seems to round in the IEEE style, determi ned in routine DLAMC1. A true IEEE machine should have both thi ngs true; however, faulty machines may have one or the other. */ ieee = ieee || lieee1; /* Compute RMIN by successive division by BETA. We could comp ute RMIN as BASE**( EMIN - 1 ), but some machines underflow dur ing this computation. */ lrmin = 1.; i__1 = 1 - lemin; for (i = 1; i <= 1-lemin; ++i) { d__1 = lrmin * rbase; lrmin = dlamc3_(&d__1, &zero); /* L30: */ } /* Finally, call DLAMC5 to compute EMAX and RMAX. */ dlamc5_(&lbeta, <, &lemin, &ieee, &lemax, &lrmax); } *beta = lbeta; *t = lt; *rnd = lrnd; *eps = leps; *emin = lemin; *rmin = lrmin; *emax = lemax; *rmax = lrmax; return 0; /* End of DLAMC2 */ } /* dlamc2_ */ #endif doublereal dlamc3_(doublereal *a, doublereal *b) { /* -- LAPACK auxiliary routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University October 31, 1992 Purpose ======= DLAMC3 is intended to force A and B to be stored prior to doing the addition of A and B , for use in situations where optimizers might hold one of these in a register. Arguments ========= A, B (input) DOUBLE PRECISION The values A and B. ===================================================================== */ /* >>Start of File<< System generated locals */ volatile doublereal ret_val; ret_val = *a + *b; return ret_val; /* End of DLAMC3 */ } /* dlamc3_ */ #ifndef HAVE_CONFIG /* Subroutine */ int dlamc4_(integer *emin, doublereal *start, integer *base) { /* -- LAPACK auxiliary routine (version 2.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University October 31, 1992 Purpose ======= DLAMC4 is a service routine for DLAMC2. Arguments ========= EMIN (output) EMIN The minimum exponent before (gradual) underflow, computed by setting A = START and dividing by BASE until the previous A can not be recovered. START (input) DOUBLE PRECISION The starting point for determining EMIN. BASE (input) INTEGER The base of the machine. ===================================================================== */ /* System generated locals */ integer i__1; doublereal d__1; /* Local variables */ static doublereal zero, a; static integer i; static doublereal rbase, b1, b2, c1, c2, d1, d2; extern doublereal dlamc3_(doublereal *, doublereal *); static doublereal one; a = *start; one = 1.; rbase = one / *base; zero = 0.; *emin = 1; d__1 = a * rbase; b1 = dlamc3_(&d__1, &zero); c1 = a; c2 = a; d1 = a; d2 = a; /* + WHILE( ( C1.EQ.A ).AND.( C2.EQ.A ).AND. $ ( D1.EQ.A ).AND.( D2.EQ.A ) )LOOP */ L10: if (c1 == a && c2 == a && d1 == a && d2 == a) { --(*emin); a = b1; d__1 = a / *base; b1 = dlamc3_(&d__1, &zero); d__1 = b1 * *base; c1 = dlamc3_(&d__1, &zero); d1 = zero; i__1 = *base; for (i = 1; i <= *base; ++i) { d1 += b1; /* L20: */ } d__1 = a * rbase; b2 = dlamc3_(&d__1, &zero); d__1 = b2 / rbase; c2 = dlamc3_(&d__1, &zero); d2 = zero; i__1 = *base; for (i = 1; i <= *base; ++i) { d2 += b2; /* L30: */ } goto L10; } /* + END WHILE */ return 0; /* End of DLAMC4 */ } /* dlamc4_ */ /* Subroutine */ int dlamc5_(integer *beta, integer *p, integer *emin, logical *ieee, integer *emax, doublereal *rmax) { /* -- LAPACK auxiliary routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University October 31, 1992 Purpose ======= DLAMC5 attempts to compute RMAX, the largest machine floating-point number, without overflow. It assumes that EMAX + abs(EMIN) sum approximately to a power of 2. It will fail on machines where this assumption does not hold, for example, the Cyber 205 (EMIN = -28625, EMAX = 28718). It will also fail if the value supplied for EMIN is too large (i.e. too close to zero), probably with overflow. Arguments ========= BETA (input) INTEGER The base of floating-point arithmetic. P (input) INTEGER The number of base BETA digits in the mantissa of a floating-point value. EMIN (input) INTEGER The minimum exponent before (gradual) underflow. IEEE (input) LOGICAL A logical flag specifying whether or not the arithmetic system is thought to comply with the IEEE standard. EMAX (output) INTEGER The largest exponent before overflow RMAX (output) DOUBLE PRECISION The largest machine floating-point number. ===================================================================== First compute LEXP and UEXP, two powers of 2 that bound abs(EMIN). We then assume that EMAX + abs(EMIN) will sum approximately to the bound that is closest to abs(EMIN). (EMAX is the exponent of the required number RMAX). */ /* Table of constant values */ static doublereal c_b5 = 0.; /* System generated locals */ integer i__1; doublereal d__1; /* Local variables */ static integer lexp; static doublereal oldy; static integer uexp, i; static doublereal y, z; static integer nbits; extern doublereal dlamc3_(doublereal *, doublereal *); static doublereal recbas; static integer exbits, expsum, try__; lexp = 1; exbits = 1; L10: try__ = lexp << 1; if (try__ <= -(*emin)) { lexp = try__; ++exbits; goto L10; } if (lexp == -(*emin)) { uexp = lexp; } else { uexp = try__; ++exbits; } /* Now -LEXP is less than or equal to EMIN, and -UEXP is greater than or equal to EMIN. EXBITS is the number of bits needed to store the exponent. */ if (uexp + *emin > -lexp - *emin) { expsum = lexp << 1; } else { expsum = uexp << 1; } /* EXPSUM is the exponent range, approximately equal to EMAX - EMIN + 1 . */ *emax = expsum + *emin - 1; nbits = exbits + 1 + *p; /* NBITS is the total number of bits needed to store a floating-point number. */ if (nbits % 2 == 1 && *beta == 2) { /* Either there are an odd number of bits used to store a floating-point number, which is unlikely, or some bits are not used in the representation of numbers, which is possible , (e.g. Cray machines) or the mantissa has an implicit bit, (e.g. IEEE machines, Dec Vax machines), which is perhaps the most likely. We have to assume the last alternative. If this is true, then we need to reduce EMAX by one because there must be some way of representing zero in an implicit-b it system. On machines like Cray, we are reducing EMAX by one unnecessarily. */ --(*emax); } if (*ieee) { /* Assume we are on an IEEE machine which reserves one exponent for infinity and NaN. */ --(*emax); } /* Now create RMAX, the largest machine number, which should be equal to (1.0 - BETA**(-P)) * BETA**EMAX . First compute 1.0 - BETA**(-P), being careful that the result is less than 1.0 . */ recbas = 1. / *beta; z = *beta - 1.; y = 0.; i__1 = *p; for (i = 1; i <= *p; ++i) { z *= recbas; if (y < 1.) { oldy = y; } y = dlamc3_(&y, &z); /* L20: */ } if (y >= 1.) { y = oldy; } /* Now multiply by BETA**EMAX to get RMAX. */ i__1 = *emax; for (i = 1; i <= *emax; ++i) { d__1 = y * *beta; y = dlamc3_(&d__1, &c_b5); /* L30: */ } *rmax = y; return 0; /* End of DLAMC5 */ } /* dlamc5_ */ #endif