# utils

* © 2006,2014,2017 John Abbott*

GNU Free Documentation License, Version 1.2

CoCoALib Documentation Index
## User documentation for file utils.H

This file defines a few very basic functions which I feel should
really be part of the standard C++. Nevertheless I have placed all
definitions inside the namespace `CoCoA`

. Here is a summary:

`round(x)`

-- round `x`

(of type `double`

) to nearest integer value (of type `double`

); halves round towards +infinity.
`ULongDiff(hi,lo)`

-- computes `hi-lo`

as **unsigned long** (assumes `hi>=lo`

)
`LongRange(lo,hi)`

-- returns a `vector<long>`

filled with `lo,lo+1,...,hi`

(useful for `submat`

)
`MaxSquarableInteger<T>()`

-- returns largest integer whose square fits in type `T`

`len(v)`

-- same as `v.size()`

except that result is `long`

rather than `size_t`

## Maintainer documentation for files utils.H

Everything is in `utils.H`

;
the functions are all so simple that they can be implemented inline.

Impl of template fn `MaxSquarableInteger`

uses GMP to compute the
memorized values. A table of constants would be faster but potentially
less portable (given that CoCoALib requires GMP anyway). I haven't yet
found a neat way of ensuring that the type `T`

is integral & bounded.

## Bugs, Shortcomings and other ideas

A possibly better idea for `MaxSquarableInteger`

: precompute 2^63*sqrt(2) as
`unsigned long`

, then simply right shift this value for integral types with
less than 127 bits. This suggestion presupposes a binary computer.

## Main changes

**2017**

- February (v0.99543): added round; removed DeleteObject and cmp template fn.
- date of first release not noted