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## [Help-gsl] float vs double and ICC

**From**: |
Gordan Bobic |

**Subject**: |
[Help-gsl] float vs double and ICC |

**Date**: |
Mon, 16 Jul 2007 16:01:28 +0100 (BST) |

Hi,
Is there a sensible way to make GSL use floats instad of doubles
internally at compile time? This may sound like a strange idea, but I am
asking becaue of performance reasons.
1) SSE1 doesn't have support for vectorized doubles, and my dev box only
has SSE1, not SSE2
2) floats are faster than doubles even with later SSE instruction sets
because twice as many get processed in parallel
3) I don't need the extra precision for my app.
The obvious bodge to pass something like -Ddouble=float breaks most
things, unsurprisingly. I don't suppose there is an option in there
somewhere to achieve this? How much am I likely to have to change if I
want to modify the multi parameter fitting engine to use floats instad of
doubles?
On a separate note, has there been any effort to test or improve automatic
vectorization of GSL libraries when compiling with ICC? I noticed that
some of the tests fail when compiling with ICC, but that could just be due
to the fact that I use optimizations that cut the odd corner on floating
point rounding for extra speed.
Thanks.
Gordan

**[Help-gsl] Exponential curve fit example**, *Gordan Bobic*, `2007/07/15`
**Re: [Help-gsl] Exponential curve fit example**, *Martin Jansche*, `2007/07/15`
**Re: [Help-gsl] Exponential curve fit example**, *Gordan Bobic*, `2007/07/16`
**[Help-gsl] float vs double and ICC**,
*Gordan Bobic* **<=**
**Re: [Help-gsl] float vs double and ICC**, *Jordi GutiĆ©rrez Hermoso*, `2007/07/16`
**[Help-gsl] Non-linear Multi-parameter Least-Squares Example**, *Gordan Bobic*, `2007/07/17`
**Re: [Help-gsl] Non-linear Multi-parameter Least-Squares Example**, *John Gehman*, `2007/07/18`
**Re: [Help-gsl] Non-linear Multi-parameter Least-Squares Example**, *Gordan Bobic*, `2007/07/18`
**Re: [Help-gsl] float vs double and ICC**, *Brian Gough*, `2007/07/19`
**Re: [Help-gsl] float vs double and ICC**, *Gordan Bobic*, `2007/07/19`
**Re: [Help-gsl] float vs double and ICC**, *Jordi GutiĆ©rrez Hermoso*, `2007/07/19`