float(%e^%e)

• Subject: float(%e^%e)
• From: Raymond Toy
• Date: 04 Oct 2002 16:41:35 -0400

>>>>> "Raymond" == Raymond Toy <toy@rtp.ericsson.se> writes:

    Raymond> A bug in FPPLUS perhaps?  However, the code for float.lisp hasn't
    Raymond> changed between 5.5 and 5.9rc1, and this isn't a problem with 5.5.

In any case, here is a test case that demonstrates the issue.

ans : -1.05b-1;
inc : -2.5186b-221;

sum : ans+ inc;

returns -1.05b-1.

But if we look at ans, inc, and the sum, we see:

:lisp $ans
((BIGFLOAT SIMP 56) -60528378991859469 -3)

:lisp $|inc|
((BIGFLOAT SIMP 56) -41001125856082033 -732)

:lisp $|sum|
((BIGFLOAT SIMP 56) -60528378991859470 -3)

So, surprisingly, the sum is now less than ans.

This surprises me since inc is so much smaller than ans.

Hope this helps someone track down this bug, if it is a bug.

Ray

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