bugAVR C Runtime Library - Bugs: bug #10413, speedup tanh function in libm

 
 

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bug #10413: speedup tanh function in libm

Submitter:  None
Submitted:  Thu 16 Sep 2004 02:41:26 PM UTC
   
 
Category:  Library Severity:  3 - Normal
Priority:  7 - High Item Group:  None
Status:  None Assigned to:  None
Percent Complete:  0% Originator Email:  -email is unavailable-
Open/Closed:  Closed Release:  None
Fixed Release:  None

Thu 16 Sep 2004 02:41:26 PM UTC, original submission:  

The current code uses sinh/cosh which results in 2 calls to exp (each function calls it once) where the other variant (commented out in tanh.S) would only need it once. (it would also save 2 calls of inverse and 1 of ldexp and saves memory by not needing cosh/sinh)

The problem is the other code has a bug. It gives to the ldexp function an 1-byte-parameter where it should be 2 bytes. (see the 2 lines before the call of ldexp.)

Appended is a file which uses this other variant and has this bug fixed. (It speedsup  my application which uses tanh extensively about 40%.)

Anonymous

 

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Attached Files
file #1772:  tanh.S added by None (4KiB - application/octet-stream - my version using the corrected other variant to calculate tanh)

 

Depends on the following items: None found

Items that depend on this one: None found

 

CC list is empty

 

Follow 3 latest changes.

Date Changed by Updated Field Previous Value => Replaced by
2004-12-22 arcanum Reassign ItemFrom group AVR C Runtime Library, bugs tracker To group AVR C Runtime Library, patch tracker
2004-12-22 arcanum Priority5 - Normal 7 - High
2004-09-16 None Attached File- Added tanh.S, #1676

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