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From: "Soegtrop, Michael" <michael DOT soegtrop AT intel DOT com>
To: "dank AT kegel DOT com" <dank AT kegel DOT com>, "cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Subject: RE: Floating point exception in strtod()
Date: Sun, 8 Apr 2018 12:57:19 +0000
Message-ID: <0F7D3B1B3C4B894D824F5B822E3E5A177861A345@IRSMSX102.ger.corp.intel.com>
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> Probably doesn't fit precisely into a double.  Does strtold behave
> better?

actually both numbers can be represented exactly as IEEE double. In Maxima:

(%i1)	factor(121645100408832000);
(%o1)	2^16*3^8*5^3*7^2*11*13*17*19
(%i2)	float(log(3^8*5^3*7^2*11*13*17*19)/log(2));
(%o2)	40.75545582601886

(%i3)	factor(221645100408832000);
(%o3)	2^16*5^3*31*41*1361*15641
(%i4)	float(log(5^3*31*41*1361*15641)/log(2));
(%o4)	41.62102908434535

So the first number has 41 bits and the second 42 after removing powers of 2. The significand size of a double is 53 bits (including the implicit 1).

Best regards,

Michael
Intel Deutschland GmbH
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