Numerical Display Functions

The following list includes both WebAssign-specific and commonly-used Perl functions that are available when creating questions.

Rounding, Significant Digits, Scientific Notation

Operation	Usage	Notes
Round to specified decimal places	`decform(n, places)`	Returns `n` rounded to the specified number of decimal `places`.
Round up (next greater integer)	`ceil(n)`	Returns the first integer greater than `n`, for example, ceil(23.2) is 24, ceil(-23.7) is -23.
Round down (next lesser integer)	`floor(n)`	Returns the first integer less than `n`, for example, floor(23.7) is 23, floor(-23.2) is - 24.
Return integer only	`int(n)`	Returns only the integer component of `n`, for example, int(23.7) is 23, int(-23.2) is - 23.
Get significant digits	`sigfigs(n)`	Returns the number of significant digits in `n`, ignoring trailing zeros.
Display significant digits	`sigform(n, digits)`	Returns `n` rounded to the specified number of significant `digits`. Uses e notation if needed, for example, 2.30e+04.
Get decimal places	`decfigs(n)`	Returns a power of 10 that represents the smallest significant decimal place in `n`. Ignores trailing zeros.
Display scientific notation	`scinot(n, digits)`	Returns `n` formatted as scientific notation with the specified number of significant `digits`, for example 2.31 × 10⁴. Do not use results for additional computation.
Display e notation	`sciform(n, digits)`	Returns `n` in e notation with up to the specified number of significant `digits` after the decimal point, for example 2.31e+04.

Display of Numerical Values

The listed functions are mostly used in Question or Solution to format values for display.

Operation	Usage	Notes
Reduced fraction	`fraction(n,d)`	Returns the fraction `n`/`d` in reduced form, for example, 1/2 or 1. If used in Answer, specify `$FRACTION=1`.
Rounded integer	`decdisplay(n)`	Returns `n` rounded to the nearest integer. Uses e notation when \|`n`\| ≥ 1e+05.
Add commas	`commas(n)`	Returns `n` with commas between digit groups to the left of the decimal point, for example, 12,345.678901. Do not use results for additional computation.
Add spaces	`spaces(n)`	Returns `n` with spaces between digit groups on both sides of the decimal point, for example, 12 345.678 901. Do not use results for additional computation.
Display as words	`spell_number(n)`	Returns the integer part of `n` in words, for example, negative twenty-three. Does not add commas.
Display as words (ordinal)	`spell_ordinal(n)`	Returns the integer part of `n` as an ordinal number in words, for example, thirteenth. Does not add commas.