Math functions in Arduino

min

min(x, y)

Description

Calculates the minimum of two numbers.

Parameters

x: the first number, any data type

y: the second number, any data type

Returns

The smaller of the two numbers.

max

max(x, y)

Description

Calculates the maximum of two numbers.

Parameters

x: the first number, any data type

y: the second number, any data type

Returns

The larger of the two parameter values.

abs

abs(x)

Description

Computes the absolute value of a number.

Parameters

x: the number

Returns

x: if x is greater than or equal to 0.

-x: if x is less than 0.

constrain

constrain(x, a, b)

Description

Constrains a number to be within a range.

Parameters

x: the number to constrain, all data types

a: the lower end of the range, all data types

b: the upper end of the range, all data types

Returns

x: if x is between a and b

a: if x is less than a

b: if x is greater than b

Example

sensVal = constrain(sensVal, 10, 150);

// limits range of sensor values to between 10 and 150

map

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

Description

Re-maps a number from one range to another. That is, a value of fromLow would get mapped to toLow, a value of fromHigh to toHigh, values in-between to values in-between, etc.

Does not constrain values to within the range, because out-of-range values are sometimes intended and useful. The constrain() function may be used either before or after this function, if limits to the ranges are desired.

Note that the "lower bounds" of either range may be larger or smaller than the "upper bounds" so the map() function may be used to reverse a range of numbers, for example

y = map(x, 1, 50, 50, 1);

The function also handles negative numbers well, so that this example

y = map(x, 1, 50, 50, -100);

is also valid and works well.

The map() function uses integer math so will not generate fractions, when the math might indicate that it should do so. Fractional remainders are truncated, and are not rounded or averaged.

Parameters

value: the number to map

fromLow: the lower bound of the value's current range

fromHigh: the upper bound of the value's current range

toLow: the lower bound of the value's target range

toHigh: the upper bound of the value's target range

Returns

The mapped value.

pow(base, exponent)

Description

Calculates the value of a number raised to a power. Pow() can be used to raise a number to a fractional power. This is useful for generating exponential mapping of values or curves.

Parameters

base: the number (float)

exponent: the power to which the base is raised (float)

Returns

The result of the exponentiation (double)