Re: [xml] XPath fix

Cyberthymia wrote:

Daniel wrote:
As a heads up, I'm working on a fix for one of the number expressions -
libxml returns 1 for the expression "5.46 mod 2.6". Apparently, according
the xsl-list, it should return "0.26" (Something to do with Java doing
floating point mods, C only doing integer mods).

The C % operator uses integer arithmetic, the C fmod() function uses
floating-point (and yields 0.26 in the above example).

 Section 3.5 of the XPath spec states:
   "This is the same as the % operator in Java and ECMAScript."
   "This is not the same as the IEEE 754 remainder operation,
    which returns the remainder from a rounding division."

So they may be right, I hate those parts where XPath/XSLT relies on Java
for the semantic of operations, it is usually a mess.

Especially when they require IEEE 754 complicancy in some situations
(e.g. NaN) but not in others.

That bit confused the heck out of me - so does that imply that Java doesn't
do IEEE 754 floating point numbers properly?

According to the Java Language Specification (section 15.17.3)

  The result of a floating-point remainder operation as computed by
  the % operator is not the same as that produced by the remainder
  operation defined by IEEE 754. The IEEE 754 remainder operation
  computes the remainder from a rounding division, not a truncating
  division, and so its behavior is not analogous to that of the usual
  integer remainder operator. Instead, the Java programming language
  defines % on floating-point operations to behave in a manner
  analogous to that of the integer remainder operator; this may be
  compared with the C library function fmod. The IEEE 754 remainder
  operation may be computed by the library routine Math.IEEEremainder.

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