dlamchf77.f File Reference

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Functions/Subroutines
DOUBLE PRECISION function	DLAMCH (CMACH)
	DLAMCH
subroutine	DLAMC1 (BETA, T, RND, IEEE1)
	DLAMC1
subroutine	DLAMC2 (BETA, T, RND, EPS, EMIN, RMIN, EMAX, RMAX)
	DLAMC2
DOUBLE PRECISION function	DLAMC3 (A, B)
	DLAMC3
subroutine	DLAMC4 (EMIN, START, BASE)
	DLAMC4
subroutine	DLAMC5 (BETA, P, EMIN, IEEE, EMAX, RMAX)
	DLAMC5

---

Function/Subroutine Documentation

DOUBLE PRECISION function DLAMC3	(	DOUBLE PRECISION	A,
		DOUBLE PRECISION	B
	)

DLAMC3

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.
 

Parameters:

[in]	A
[in]	B	The values A and B.

Definition at line 671 of file dlamchf77.f.

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subroutine DLAMC4	(	INTEGER	EMIN,
		DOUBLE PRECISION	START,
		INTEGER	BASE
	)

DLAMC4

Purpose:

 DLAMC4 is a service routine for DLAMC2.
 

Parameters:

[out]	EMIN	The minimum exponent before (gradual) underflow, computed by setting A = START and dividing by BASE until the previous A can not be recovered.
[in]	START	The starting point for determining EMIN.
[in]	BASE	The base of the machine.

Definition at line 718 of file dlamchf77.f.

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subroutine DLAMC5	(	INTEGER	BETA,
		INTEGER	P,
		INTEGER	EMIN,
		LOGICAL	IEEE,
		INTEGER	EMAX,
		DOUBLE PRECISION	RMAX
	)

DLAMC5

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.
 

Parameters:

[in]	BETA	The base of floating-point arithmetic.
[in]	P	The number of base BETA digits in the mantissa of a floating-point value.
[in]	EMIN	The minimum exponent before (gradual) underflow.
[in]	IEEE	A logical flag specifying whether or not the arithmetic system is thought to comply with the IEEE standard.
[out]	EMAX	The largest exponent before overflow
[out]	RMAX	The largest machine floating-point number.

Definition at line 825 of file dlamchf77.f.

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