Adding numbers

Add floating point numbers with full precision.

new Adder()

const adder = new d3.Adder();

Examples · Source · Creates a new adder with an initial value of 0.

adder.add(number)

adder.add(42)

Adds the specified number to the adder’s current value and returns the adder.

adder.valueOf()

adder.valueOf() // 42

Returns the IEEE 754 double-precision representation of the adder’s current value. Most useful as the short-hand notation +adder, or when coercing as Number(adder).

fsum(values, accessor)

d3.fsum([0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1]) // 1

Examples · Source · Returns a full-precision summation of the given values. Although slower, d3.fsum can replace d3.sum wherever greater precision is needed.

d3.fsum(penguins, (d) => d.body_mass_g) // 1437000

If an accessor is specified, invokes the given function for each element in the input values, being passed the element d, the index i, and the array data as three arguments; the returned values will then be added.

fcumsum(values, accessor)

d3.fcumsum([1, 1e-14, -1]) // [1, 1.00000000000001, 1e-14]

Examples · Source · Returns a full-precision cumulative sum of the given values as a Float64Array. Although slower, d3.fcumsum can replace d3.cumsum when greater precision is needed.

d3.fcumsum(penguins, (d) => d.body_mass_g) // [3750, 7550, 10800, 10800, 14250, …]

If an accessor is specified, invokes the given function for each element in the input values, being passed the element d, the index i, and the array data as three arguments; the returned values will then be added.