Wed, 23 Nov 1994 22:03:45 GMT

Newsgroups: | comp.parallel,comp.arch,comp.compilers |

From: | koppel@omega.ee.lsu.edu (David M. Koppelman) |

In-Reply-To: | zxu@monalisa.usc.edu's message of Wed, 23 Nov 1994 00:38:40 GMT |

Status: | R |

Originator: | rmuise@dragon.acadiau.ca |

Organization: | Louisiana State University ECE Dept. |

References: | <3aqv5k$e27@monalisa.usc.edu> |

Date: | Wed, 23 Nov 1994 22:03:45 GMT |

In article <3aqv5k$e27@monalisa.usc.edu> zxu@monalisa.usc.edu (Zhiwei Xu) writes:

*> Can any one explain why a C program using single precision (float) is slower*

*> that the same code using double precision (double)? Please try the following*

*> code for computing pi. I have tried it on IBM RS6000/250, IBM SP2, Sun4, and*

*> Sun SS20, and got the same strange timing.*

In the RS/6000 all floating point is double precision. When you specify

single-precision operations the double precision result is rounded,

this takes more time. Also, C (at least some implementations) does

computation in double-precision by default.

Post a followup to this message

Return to the
comp.compilers page.

Search the
comp.compilers archives again.