cos(1.0d97) with GCL, Clozure, and Julia

• Subject: cos(1.0d97) with GCL, Clozure, and Julia
• From: Barton Willis
• Date: Thu, 10 May 2012 12:01:43 +0000

With GCL:

 (%i63) cos(1.0d97);
 (%o63) 0.44800964805919

With Julia or Clozure CL:

julia> cos(1.0e97)
0.7496172085944125

$ wx86cl64
Welcome to Clozure Common Lisp Version 1.8-r15286M  (WindowsX8664)!
? (cos 1.0d97)
0.7496172085944125D0

And bigfloats:

 (%i60) cos(1.0b97), fpprec : 2000;
 (%o60) -7.0797267715593222213703559504[1944 digits]888604264163488232493341331b-2

Let me guess that Clozure & Julia turn the calculation entirely over to the (Intel) microprocessor. What on earth does GCL do?
Is this a binary32 / binary64 confusion problem? 

No, I'm not surprised that the Clozure & Julia values are likely completely  wrong--it just makes me wonder what GCL is doing.

--bw

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