Math

Rescaling and limiting numbers: map() and constrain(). More...

Functions
	map (value, fromLow, fromHigh, toLow, toHigh)
	Rescales a number from one range to another.
	constrain (value, low, high)
	Limits a number to a range.

Detailed Description

Rescaling and limiting numbers: map() and constrain().

Function Documentation

map()

map	(		value,
			fromLow,
			fromHigh,
			toLow,
			toHigh )

Rescales a number from one range to another.

With whole numbers the result is a whole number, rounded towards zero as on an Arduino; with any float it is a float. Not clamped: use constrain().

Parameters

value	The number to rescale.
fromLow	Bottom of the range value is in.
fromHigh	Top of the range value is in.
toLow	Bottom of the new range.
toHigh	Top of the new range.

Returns

The rescaled number.

Example

analogWrite(3, map(analogRead(A0), 0, 1023, 0, 255))

constrain()

constrain	(		value,
			low,
			high )

Limits a number to a range.

Parameters

value	The number.
low	The smallest result.
high	The largest result.

Returns

low if value is below it, high if above it, otherwise value.

Example

level = constrain(reading, 0, 255)  # keeps level in analogWrite()'s range