graduate Pretty axis graduations

## Syntax

    [xi,xa,np]=graduate( xmi, xma,n1,n2)
                [xi,xa,np]=graduate( xmi, xma)

## Arguments

xmi,xma

  real scalars

n1, n2

  integers with default values 3,10

xi, xa

  real scalars

np

  integer

## Description

graduate looks for the minimum interval `[xi,xa]` and a number of tics `np` such that:

`xi <= xmi <= xma <= xa`

`xa - xi / np = k(10^n)`,`k` in `[1 3 5]` for an integer `n`

`n1 < np < n2`

## Examples

    y = (0:0.33:145.78)';
    clf();
    subplot(1,2,1)
    plot2d(y)

    subplot(1,2,2)
    [ymn,ymx,np] = graduate(min(y), max(y))
    rect = [1, ymn, prod(size(y)),ymx];
    plot2d([], y, 1,'011',' ',rect,[10,3,10,np])

## See also

- xsetech
- plot2d