GNU Octave Manual Version 3by John W. Eaton, David Bateman, Søren Hauberg Paperback (6"x9"), 568 pages ISBN 095461206X RRP £24.95 ($39.95) |

### 14.1.4 Rational Approximations

__Function File:__`s`=**rat***(*`x`,`tol`)__Function File:__[`n`,`d`] =**rat***(*`x`,`tol`)-
Find a rational approximation to

`x`within tolerance defined by`tol`using a continued fraction expansion. E.g,rat(pi) = 3 + 1/(7 + 1/16) = 355/113 rat(e) = 3 + 1/(-4 + 1/(2 + 1/(5 + 1/(-2 + 1/(-7))))) = 1457/536

Called with two arguments returns the numerator and denominator separately as two matrices.

See also rats

__Built-in Function:__**rats***(*`x`,`len`)- Convert
`x`into a rational approximation represented as a string. You can convert the string back into a matrix as follows:r = rats(hilb(4)); x = str2num(r)

The optional second argument defines the maximum length of the string representing the elements of

`x`. By default`len`is 9.See also format, rat

ISBN 095461206X | GNU Octave Manual Version 3 | See the print edition |