Function differenceFromLast

differenceFromLast(
kind?: DifferenceKind,
initialValue?: number,
): (v: number) => number
Returns a function which yields difference compared to last value.

If no initial value is provided, the first difference will be returned as 0.

Difference can be returned in various formats:
- 'absolute': numerical difference, without sign
- 'numerical': numerical difference, with sign, so you can see if difference is higher or lower
- 'relative': difference divided by last value, giving a proportional difference. Unsigned.
- 'relativeSigned': as above, but with sign
Use differenceFromFixed to compare against a fixed value instead of the last value.
```
let d = differenceFromLast(`absolute`);
d(10); // 0
d(11); // 1
d(10); // 1
```
```
let d = differenceFromLast(`numerical`);
d(10); // 0
d(11); // 1
d(10); // -1
```
```
let d = differenceFromLast(`relative`);
d(10); // 0
d(11); // 0.1
d(10); // 0.1
```
```
let d = differenceFromLast(`relativeSigned`);
d(10); // 0
d(11); // 0.1
d(10); // -0.1
```
An initial value can be provided, eg:
```
let d = differenceFromLast(`absolute`, 10);
d(11); // 1
```
Parameters
- kind: DifferenceKind = ...
  Kind of output value
- initialValue: number = Number.NaN
  Optional initial value
Returns (v: number) => number