XSLT math

Using math in XSLT: http://www.xml.com/pub/a/2001/05/07/xsltmath.html

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   version="1.0">
<xsl:output method="xml" omit-xml-declaration="yes"/>

<xsl:template match="numbers">
A. 4 + 3.2        = <xsl:value-of select="x + y"/>
B. 3.2 - 4        = <xsl:value-of select="y - x"/>
C. 4 * 3.2        = <xsl:value-of select="x * y"/>
D. 11/3.2         = <xsl:value-of select="z div y"/>
E. 4 + 3.2 * 11   = <xsl:value-of select="x+y*z"/>
F. (4 + 3.2) * 11 = <xsl:value-of select="(x+y)*z"/>
G. 11 mod 4       = <xsl:value-of select="z mod x"/>
H. 4 + 3.2 + 11   = <xsl:value-of select="sum(*)"/>
I. floor(3.2)     = <xsl:value-of select="floor(y)"/>
J. ceiling(3.2)   = <xsl:value-of select="ceiling(y)"/>
K. round(3.2)     = <xsl:value-of select="round(y)"/>
L. 11 + count(*)  = <xsl:value-of select="11+count(*)"/>
M. 3.2 + string-length("3.2") =
   <xsl:value-of select="y + string-length(y)"/>
N. 11 + "hello"     = <xsl:value-of select="z + 'hello'"/>
</xsl:template>

</xsl:stylesheet>

Warning With some XSLT processors, the use of decimal numbers may introduce a tiny error. For example, the "3.2 - 4" in this example comes out as "-.7999999999999998" on some processors. While being off by .0000000000000002 isn't much, being off at all shows that math is not XSLT's strong point.

Combinations, permuations and iterations

To generate all combinations or permutations of a fixed list, use Math::Combinatorics

To generate sequential values for a set of slots, e.g. all binary numbers, or the number of 'max_results' for several modules do this:

1. add one to the first slot
2. if that takes it over the maximum, set it to zero and add one to the next slot
3. repeat step 2 until you reach all zeroes
4. if all zeroes, you are finished.
   

Bash variable comparisons

...bash logic...

Note that integer and string comparison use a different set of operators.

integer comparison

-eq

is equal to

if [ "$a" -eq "$b" ]

-ne

is not equal to

if [ "$a" -ne "$b" ]

-gt

is greater than

if [ "$a" -gt "$b" ]

-ge

is greater than or equal to

if [ "$a" -ge "$b" ]

-lt

is less than

if [ "$a" -lt "$b" ]

-le

is less than or equal to

if [ "$a" -le "$b" ]

<

is less than (within double parentheses)

(("$a" < "$b"))

<=

is less than or equal to (within double parentheses)

(("$a" <= "$b"))

>

is greater than (within double parentheses)

(("$a" > "$b"))

>=

is greater than or equal to (within double parentheses)

(("$a" >= "$b"))

string comparison

=

is equal to

if [ "$a" = "$b" ]

==

is equal to

if [ "$a" == "$b" ]

This is a synonym for =.

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