[Issue 15365] std.math: 80-bit exp() tests are utterly wrong when returning subnormals

via Digitalmars-d-bugs digitalmars-d-bugs at puremagic.com
Fri Nov 20 07:53:43 PST 2015


https://issues.dlang.org/show_bug.cgi?id=15365

--- Comment #1 from Don <clugdbug at yahoo.com.au> ---
Note that these errors occur only in the slow path of the asm exp(). Thus, a
more accurate, slower calculation can be added with no impact on speed.

Clearly, there is a loss of precision bug. I am not certain, but the problem
may be in the extraction of the integer part, which is obviously limited to 64
bits.
I need to look into this.

This title of this bug report is a bit alarmist though, it's not very generous
to describe 52 bit accurate as "utterly wrong". :)

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