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| 2 | 1 | equemene | <HEAD>
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| 3 | 1 | equemene | <TITLE>HPL_pdlamch HPL 2.0 Library Functions September 10, 2008</TITLE> |
| 4 | 1 | equemene | </HEAD>
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| 6 | 1 | equemene | <BODY BGCOLOR="WHITE" TEXT = "#000000" LINK = "#0000ff" VLINK = "#000099" |
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| 8 | 1 | equemene | |
| 9 | 1 | equemene | <H1>Name</H1> |
| 10 | 1 | equemene | <B>HPL_pdlamch</B> determines machine-specific arithmetic constants. |
| 11 | 1 | equemene | |
| 12 | 1 | equemene | <H1>Synopsis</H1> |
| 13 | 1 | equemene | <CODE>#include "hpl.h"</CODE><BR><BR> |
| 14 | 1 | equemene | <CODE>double</CODE> |
| 15 | 1 | equemene | <CODE>HPL_pdlamch(</CODE> |
| 16 | 1 | equemene | <CODE>MPI_Comm</CODE> |
| 17 | 1 | equemene | <CODE>COMM</CODE>, |
| 18 | 1 | equemene | <CODE>const HPL_T_MACH</CODE> |
| 19 | 1 | equemene | <CODE>CMACH</CODE> |
| 20 | 1 | equemene | <CODE>);</CODE> |
| 21 | 1 | equemene | |
| 22 | 1 | equemene | <H1>Description</H1> |
| 23 | 1 | equemene | <B>HPL_pdlamch</B> |
| 24 | 1 | equemene | determines machine-specific arithmetic constants such as |
| 25 | 1 | equemene | the relative machine precision (eps), the safe minimum(sfmin) such that |
| 26 | 1 | equemene | 1/sfmin does not overflow, the base of the machine (base), the precision |
| 27 | 1 | equemene | (prec), the number of (base) digits in the mantissa (t), whether |
| 28 | 1 | equemene | rounding occurs in addition (rnd = 1.0 and 0.0 otherwise), the minimum |
| 29 | 1 | equemene | exponent before (gradual) underflow (emin), the underflow threshold |
| 30 | 1 | equemene | (rmin)- base**(emin-1), the largest exponent before overflow (emax), the |
| 31 | 1 | equemene | overflow threshold (rmax) - (base**emax)*(1-eps). |
| 32 | 1 | equemene | |
| 33 | 1 | equemene | <H1>Arguments</H1> |
| 34 | 1 | equemene | <PRE>
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| 35 | 1 | equemene | COMM (global/local input) MPI_Comm |
| 36 | 1 | equemene | The MPI communicator identifying the process collection. |
| 37 | 1 | equemene | </PRE>
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| 38 | 1 | equemene | <PRE>
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| 39 | 1 | equemene | CMACH (global input) const HPL_T_MACH |
| 40 | 1 | equemene | Specifies the value to be returned by HPL_pdlamch |
| 41 | 1 | equemene | = HPL_MACH_EPS, HPL_pdlamch := eps (default) |
| 42 | 1 | equemene | = HPL_MACH_SFMIN, HPL_pdlamch := sfmin |
| 43 | 1 | equemene | = HPL_MACH_BASE, HPL_pdlamch := base |
| 44 | 1 | equemene | = HPL_MACH_PREC, HPL_pdlamch := eps*base |
| 45 | 1 | equemene | = HPL_MACH_MLEN, HPL_pdlamch := t |
| 46 | 1 | equemene | = HPL_MACH_RND, HPL_pdlamch := rnd |
| 47 | 1 | equemene | = HPL_MACH_EMIN, HPL_pdlamch := emin |
| 48 | 1 | equemene | = HPL_MACH_RMIN, HPL_pdlamch := rmin |
| 49 | 1 | equemene | = HPL_MACH_EMAX, HPL_pdlamch := emax |
| 50 | 1 | equemene | = HPL_MACH_RMAX, HPL_pdlamch := rmax |
| 51 | 1 | equemene | |
| 52 | 1 | equemene | where |
| 53 | 1 | equemene | |
| 54 | 1 | equemene | eps = relative machine precision, |
| 55 | 1 | equemene | sfmin = safe minimum, |
| 56 | 1 | equemene | base = base of the machine, |
| 57 | 1 | equemene | prec = eps*base, |
| 58 | 1 | equemene | t = number of digits in the mantissa, |
| 59 | 1 | equemene | rnd = 1.0 if rounding occurs in addition, |
| 60 | 1 | equemene | emin = minimum exponent before underflow, |
| 61 | 1 | equemene | rmin = underflow threshold, |
| 62 | 1 | equemene | emax = largest exponent before overflow, |
| 63 | 1 | equemene | rmax = overflow threshold. |
| 64 | 1 | equemene | </PRE>
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| 66 | 1 | equemene | </BODY>
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| 67 | 1 | equemene | </HTML> |