# Number

A mathematical concept used to count, measure and do other maths stuff.

## Declaration

The `Number`

type is implemented as `double`

. Here's how to declare a number:

```
a = 5 # number declaration (immutable)
b: Number = 5 # same effect, with type-checking
c: Number = a # initiating from entry value, also 5
d = 43.14 # with decimals
```

To declare a mutable entry, prepend it with the tilde operator:

```
~ a = 6 # mutable number entry
a += 1 # adds 1 to 'a', yields 7
```

## Operating numbers

Numbers accept quite a few operations:

`==`

equal`!=`

not equal`+`

plus`-`

minus`*`

multiply`/`

divide`%`

modulus`**`

power`<`

less`<=`

less or equal`>`

more`>=`

more or equal`&`

logical AND`|`

logical OR

### Caveats

For logical operations and flow control, keep in mind that zero is falsy and non-zero is truthy.

For equality operators, although `0`

and `null`

are evaluated as falsy, in FatScript they are not the same:

```
0 == null # false
```

## Precision

Although the arithmetic precision of a `IEEE 754 double`

is higher, `fry`

employs rounding tricks to improve human readability when printing long decimal sequences of nines or zeros as text. Additionally, it uses an epsilon of `1.0e-06`

for 'equality' comparisons between numbers.

In 99.999% of use cases, this approach provides both more convenient comparisons and more natural-looking numbers:

```
# Equality epsilon
x = 1.0e-06
x: Number = 0.000001
# Smaller differences are treated as the "same" number by comparison
x == 0.0000015
Boolean: true # the 0.0000005 difference is ignored
```

Floating-point numbers aren't distributed evenly on the number line. They are dense around 0, and as the magnitude increases, the 'delta' between two expressible values increases:

```
_____________________________________0_____________________________________
+inf | | | | | | | ||| | | | | | | | -inf
```

the biggest contiguous integer is 9,007,199,254,740,992 or 2^53

You can still have much larger numbers, around 10^308, which is:

```
100000000000000000000000000000000000000000000000000000000000000000000000000000
000000000000000000000000000000000000000000000000000000000000000000000000000000
000000000000000000000000000000000000000000000000000000000000000000000000000000
000000000000000000000000000000000000000000000000000000000000000000000000000
```

Bear in mind that if you add 1 to 10^308, no matter how many times you do it, it will always result in the same value! You need to add at least something near 10^293 in a single operation for it to be considered, as the numbers need to be of similar orders of magnitude.