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Compiler/LAUNCHXL-F28069M: Reassociation of FP arithmetic

user4957458
Expert 1065 points

Part Number: LAUNCHXL-F28069M

Tool/software: TI C/C++ Compiler

Dear all

     Can anyone explain what "Allow reassociation of FP arithmetic" ON an OFF does? What is reassociated?

Thanks

Luis Gonçalves

  • 0
    Expert 2530 points
    x * 5.0 / 15.0 after reassociation will turn into x * 0.33333333..

    Since FP operations not very often give exact results, proper C compiler should never reassociate FP operations, it should first multiply by 5, then divide by 15. Even replacing /15 with *0.06666... is not allowed. But for better performance you may set this option to ON, of course if you don't mind side effects of reassociation.

    Edward
  • 0 in reply to EK
    TI__Genius 17315 points
    Luis,

    Hopefully this answers your question.

    Thanks EK for your help.

    - Ken