Check if two values are equal within a given tolerance.

Float.equalWithin 1e-6 1.9999 2.0001
--> False


Float.equalWithin 1e-3 1.9999 2.0001
--> True

Interpolate from the first value to the second, based on a parameter that ranges from zero to one. Passing a parameter value of zero will return the start value and passing a parameter value of one will return the end value.

Float.interpolateFrom 5 10 0
--> 5


Float.interpolateFrom 5 10 1
--> 10


Float.interpolateFrom 5 10 0.6
--> 8

The end value can be less than the start value:

Float.interpolateFrom 10 5 0.1
--> 9.5

Parameter values less than zero or greater than one can be used to extrapolate:

Float.interpolateFrom 5 10 1.5
--> 12.5


Float.interpolateFrom 5 10 -0.5
--> 2.5


Float.interpolateFrom 10 5 -0.2
--> 11

Construct a range of evenly-spaced values given a start value, an end value and the number of steps to take from the start to the end. The first value in the returned list will be equal to start and the last value will be equal to end. Note that the number of returned values will be one greater than the number of steps!

Float.range { start = 0, end = 1, steps = 1 }
--> [ 0, 1 ]


Float.range { start = 0, end = 1, steps = 2 }
--> [ 0, 0.5, 1 ]


Float.range { start = 10, end = 20, steps = 2 }
--> [ 10, 15, 20 ]


Float.range { start = 2, end = 3, steps = 5 }
--> [ 2, 2.2, 2.4, 2.6, 2.8, 3 ]

The start and end values can be in either order:

Float.range { start = 1, end = 3, steps = 4 }
--> [ 1, 1.5, 2, 2.5, 3 ]


Float.range { start = 3, end = 1, steps = 4 }
--> [ 3, 2.5, 2, 1.5, 1 ]

Passing a negative or zero steps value will result in an empty list being returned.

If you need finer control over what values get generated, try combining interpolateFrom with the various functions in the elm-1d-parameter package. For example:

-- Same as using Float.range
Parameter1d.steps 5 (Float.interpolateFrom 2 3)
--> [ 2, 2.2, 2.4, 2.6, 2.8, 3 ]


-- Omit the last value
Parameter1d.leading 5 (Float.interpolateFrom 2 3)
--> [ 2, 2.2, 2.4, 2.6, 2.8 ]


-- Omit the first value
Parameter1d.trailing 5 (Float.interpolateFrom 2 3)
--> [ 2.2, 2.4, 2.6, 2.8, 3 ]