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Wherefore abs()?

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  • John E. Simpson
    Just out of curiosity, can anyone suggest a practical application for the abs() function as defined by section 5.10.1 of the CR? I can certainly see that the
    Message 1 of 3 , Apr 13, 2001
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      Just out of curiosity, can anyone suggest a practical application for the
      abs() function as defined by section 5.10.1 of the CR?

      I can certainly see that the numbers you'd be dealing with in an XSL-FO
      context (e.g., column numbers, dimensions, page numbers, colors...) ought
      to be greater than 0. What I'm having a hard time imagining is how they'd
      start out less than 0 in the first place, and therefore need "correction"
      using abs().

      Can anyone provide a practical use case for abs(), other than a simple
      desire for completeness?

      (The spec, not surprisingly, seems to include only one occurrence of the
      string "abs(" -- that being in section 5.10.1 itself. Anyone have any idea
      how the "core function library" in general applies to conformance? Are all
      core functions assumed to be part of XSL-FO at the basic conformance level?)

      ================================================================
      John E. Simpson | "I have a microwave fireplace.... The
      http://www.flixml.org | other night I laid down in front of
      XML Q&A: www.xml.com | the fire for the evening in two minutes."
      | --Steven Wright
    • Dave Hartnoll
      I can t answer your specific question about a practical application for abs() because I haven t used XSL-FO yet, but I can offer this: abs() is often used to
      Message 2 of 3 , Apr 19, 2001
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        I can't answer your specific question about a practical application for
        abs() because I haven't used XSL-FO yet, but I can offer this: abs() is
        often used to find the positive difference between two numbers (or
        sub-expressions) without having to know which is the bigger and which is the
        smaller. For example, to get the difference between A and B you could say
        abs(A-B) OR abs(B-A).

        Dave.

        ----- Original Message -----
        From: "John E. Simpson" <simpson@...>
        To: <XSL-FO@yahoogroups.com>
        Sent: Friday, April 13, 2001 8:15 PM
        Subject: [XSL-FO] Wherefore abs()?


        > Just out of curiosity, can anyone suggest a practical application for the
        > abs() function as defined by section 5.10.1 of the CR?
        >
        > I can certainly see that the numbers you'd be dealing with in an XSL-FO
        > context (e.g., column numbers, dimensions, page numbers, colors...) ought
        > to be greater than 0. What I'm having a hard time imagining is how they'd
        > start out less than 0 in the first place, and therefore need "correction"
        > using abs().
        >
        > Can anyone provide a practical use case for abs(), other than a simple
        > desire for completeness?
        >
        > (The spec, not surprisingly, seems to include only one occurrence of the
        > string "abs(" -- that being in section 5.10.1 itself. Anyone have any idea
        > how the "core function library" in general applies to conformance? Are all
        > core functions assumed to be part of XSL-FO at the basic conformance
        level?)
        >
        > ================================================================
        > John E. Simpson | "I have a microwave fireplace.... The
        > http://www.flixml.org | other night I laid down in front of
        > XML Q&A: www.xml.com | the fire for the evening in two minutes."
        > | --Steven Wright
        >
        >
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        >
        >
      • John E. Simpson
        ... Thanks for the reply, Dave. I d taken the list s silence for assent. :) That s a good point, too -- about using abs() to express not the absolute value of
        Message 3 of 3 , Apr 19, 2001
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          Dave Hartnoll wrote:

          > I can't answer your specific question about a practical application for
          > abs() because I haven't used XSL-FO yet, but I can offer this: abs() is
          > often used to find the positive difference between two numbers (or
          > sub-expressions) without having to know which is the bigger and which is the
          > smaller. For example, to get the difference between A and B you could say
          > abs(A-B) OR abs(B-A).

          Thanks for the reply, Dave. I'd taken the list's silence for assent. :)

          That's a good point, too -- about using abs() to express not the
          absolute value of a single number, but of the difference between two --
          and one I should have thought of myself. In XSL-FO terms, maybe this
          might be useful given the absolute positions and sizes of two areas, in
          determining the distance from one area to the next....

          I'll think some more on it. Thanks again.
          ================================================================
          John E. Simpson | "When I was a little kid we had a sand
          http://www.flixml.org | box. It was a quicksand box. I was an
          XML Q&A: www.xml.com | only child... eventually." (Steven Wright)
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