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From: ghe@mist.cs.orst.edu (Guangliang He)
Newsgroups: comp.lang.fortran
Subject: Re: complex*32?
Message-ID: <15749@orstcs.CS.ORST.EDU>
Date: 12 Feb 90 19:26:58 GMT
References: <9002120228.AA19489@euler.Berkeley.EDU> <1990Feb12.140657.28884@deimos.cis.ksu.edu>
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Reply-To: ghe@mist.CS.ORST.EDU (Guangliang He)
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In article <1990Feb12.140657.28884@deimos.cis.ksu.edu> mac@harris.cis.ksu.edu (Myron A. Calhoun) writes:
|
|Also, I question ANYONE'S need for 32 bytes * 8 bits/byte minus
|12 (bits for exponent and two signs) = 244 bits ~= 74 digits
|of precision!  If I remember correctly:
|   if one knew the value of PI to 50 digits,
|   if one knew the radius of the whole universe EXACTLY, and
|   if one used both to calculate the diameter of the universe,
|   then adding a 51st digit to PI and recalculating the diameter would
|        not give a value enough larger to slip a playing card between them.
|
|So I find it hard to believe such precision is necessary.
|
|But I've been wrong before and will undoubtedly be wrong again!
|--Myron.

But life isn't that simple. When you are solving a large dimension ill 
conditioned matrix problems, the round-off error will be significant. 
Then the more precision really helps.

ghe@mist.cs.orst.edu