## Forum archive 2000-2006

### Michael Gage - inv_romberg

by Arnold Pizer -
Number of replies: 0
 inv_romberg topic started 8/28/2001; 8:18:46 PMlast post 8/28/2001; 8:18:46 PM
Michael Gage - inv_romberg
8/28/2001; 8:18:46 PM (reads: 1845, responses: 0)

### inv_romberg

Syntax
$right_hand_endpoint = inv_romberg($rf_func, $left_hand_endpoint,$value) ;

Params

$rf_func refers to a subroutine of one variable defining the function. $left_hand_endpoint is the left hand endpoint of the integral.
$value is the desired value for the integral. Returns A number representing the right hand endpoint of the interval whose definite integral has the desired value. Examples $b = inv_romberg(sub { my $x=shift; (1/sqrt($PI) )*exp(-\$x**2); }, 0, 1/4);
# find the upper limit b so that the area under the normal distribution on the inteval between 0 and b is 1/4.

Notes

Can be used, for example, to find intervals under a normal distribution curve that have a desired value. Used in many statistics problems.