[Maxima-bugs] [ maxima-Bugs-2582731 ] wrong sine computation

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Bugs item #2582731, was opened at 2009-02-09 16:18
Message generated for change (Comment added) made by rtoy
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>Category: Lisp Core
Group: To be reviewed
>Status: Pending
>Resolution: Invalid
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: wrong sine computation

Initial Comment:
tried this on Linux and Windows:
fpprec:70;
bfloat(asin(sin(0.1)))

should be 0.1, results in a number > 1

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>Comment By: Raymond Toy (rtoy)
Date: 2009-02-13 09:25

Message:
Marking as pending/invalid.

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Comment By: Raymond Toy (rtoy)
Date: 2009-02-09 16:23

Message:
Please show exactly what you got.

I get the following:

(%i133) bfloat(asin(sin(0.1)));
(%o133)   1.000000000000000055511151231257827021181583404541015625b-1

This is the expected answer because bfloat(0.1) is precisely %o133.
(0.1 is a double-float which doesn't have an exact floating-point
representation.  The conversion to bfloat shows that.)




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