IEEE special values

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  • Norbert Nemec
    #1

    IEEE special values

    Hi there,

    is there any simple reason why IEEE special values are so poorly supported
    in python? Are there any serious efforts to change that? NaN and Inf are an
    extremely useful concept for numerical calculations and they would mix
    perfectly with the concepts in NumPy, anyhow, the support seems to be
    absolutely minimal.

    (The ideas in PEP 754 do not really change much: There is little use in easy
    access to those values, if the math functions don't accept them as input
    but break down.)

    Ciao,
    Nobbi
    Tags: None
    • John Roth
      #2
      Re: IEEE special values


      "Norbert Nemec" <nobbi_at_theor ie3.physik.uni-erlangen.de@NOS PAM.COM> wrote
      in message news:bhl7bi$ggg $1@rznews2.rrze .uni-erlangen.de...[color=blue]
      > Hi there,
      >
      > is there any simple reason why IEEE special values are so poorly supported
      > in python? Are there any serious efforts to change that? NaN and Inf are[/color]
      an[color=blue]
      > extremely useful concept for numerical calculations and they would mix
      > perfectly with the concepts in NumPy, anyhow, the support seems to be
      > absolutely minimal.
      >
      > (The ideas in PEP 754 do not really change much: There is little use in[/color]
      easy[color=blue]
      > access to those values, if the math functions don't accept them as input
      > but break down.)[/color]

      Like a lot of things, Python's math functions are a rather thin layer
      on top of the native C library's math functions. If the C library's
      math functions, to use the vernacular, suck, then Python's math
      functions will do likewise.

      One of the essential problems is that every library does certain
      things differently, like deciding whether it's going to start up with
      silent or signaling NaN's, or what the actual string values are for
      NaN, infinity and so forth.

      It takes developer time to clean up that situation. I suspect
      that volunteers would be very welcome.

      John Roth
      [color=blue]
      >
      > Ciao,
      > Nobbi[/color]


        Comment

        • Terry Reedy
          #3
          Re: IEEE special values


          "Norbert Nemec" <nobbi_at_theor ie3.physik.uni-erlangen.de@NOS PAM.COM>
          wrote in message news:bhl7bi$ggg $1@rznews2.rrze .uni-erlangen.de...
          [color=blue]
          > is there any simple reason why IEEE special values are so poorly[/color]
          supported[color=blue]
          > in python?[/color]

          A. They are poorly, and just as importantly, inconsistently supported
          in C.
          B. Python's floating point arithmetic and standard functions are thin
          wrappers of the C layer.

          TJR


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