Help:Modulo and round

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The MediaWiki extension ParserFunctions enables users to perform simple mathematical computations.

#expr and #ifexpr allow mod and round.

Operator Operation Example
mod "Modulo", remainder of division after truncating both operands to an integer.

Caveat, mod is different from all programming languages. This has been fixed (but needs to be committed), see bugzilla:6068. 		Template:Evaldemo
Template:Evaldemo
Template:Evaldemo
Template:Evaldemo (should be 2.6)
Template:Evaldemo (should be 1.6)
Template:Evaldemo (should be 2.9)
round Rounds off the number on the left to the power of 1/10 given on the right Template:Evaldemo
Template:Evaldemo
{{ #expr: 3456 round -2}} = {{#expr: 3456 round -2}}

Spaces around mod and round are good for readability but not needed for working properly:

Precedence:

(first additions, then round)

(mod and multiplication have equal precedence, evaluation from left to right)

To remind the reader of the precedence, one might write:

When using spaces where there is precedence, the layout of the expression may be confusing:
Template:Evaldemo
Instead one can write:
Template:Evaldemo
or simply use parentheses:
Template:Evaldemo

Mod

To get a positive mod even for a negative number, use e.g. (700000 + x) mod7 instead of x mod7. The range of the result is now 0-6, provided that x > -700000.

Alternatively, use

or

The range of the result is 0-6, provided that x < 700006.

Working for all x is:

Round

To round an integer plus one half for x > -100000 toward plus infinity, use:

and to round an integer plus one half for x < 100000 toward minus infinity, use:

To round x toward minus infinity, use:

and toward plus infinity

If x is a long expression this multiplies the length by 5! Under conditions for x there are alternatives:

To round x > -100000 toward minus infinity, use:

and to round x < 100000 toward plus infinity, use:

If x is a multiple of 1/n with n<1000 we can round toward minus infinity with:

For arbitrary n > 1 we can choose instead of -.499 any number between -.5 and -.5 + 1/n.

To find the largest multiple of 7 not larger than x (i.e. to round toward minus infinity to a multiple of 7) we can do:

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