k-Wave Toolbox |

# checkFactors

Return the maximum prime factor for a range of numbers

## Syntax

    checkFactors(min_number, max_number)

## Description

`checkFactors` loops through the given range of numbers and finds the numbers with the smallest maximum prime factors. This allows suitable grid sizes to be selected to maximise the speed of the FFT (this is fastest for FFT lengths with small prime factors).

For example, running the code `checkFactors(100, 200)` produces the output

    Numbers with a maximum factor of 2
    128
    Numbers with a maximum factor of 3
    108  144  162  192
    Numbers with a maximum factor of 5
    100  120  125  135  150  160  180  200
    Numbers with a maximum factor of 7
    105  112  126  140  147  168  175  189  196

## See Also

`fft`, `factor`

© 2009, 2010, 2011 Bradley Treeby and Ben Cox.