IDL Reference Guide: Procedures and Functions |

The PNT_LINE function computes the perpendicular distance between a point *P0* and a line between points *L0* and *L1*. This function is limited by the machine accuracy of single precision floating point.

This routine is written in the IDL language. Its source code can be found in the file `pnt_line.pro`

in the `lib`

subdirectory of the IDL distribution.

*Result* = PNT_LINE( *P0*, *L0*, *L1* [, *Pl*] [, /INTERVAL] )

Returns the perpendicular distance.

The location of the point. *P0* may have 2 to *n* elements, for *n* dimensions.

One end-point of the line. *L0* must have same number of elements as *P0*.

The other end-point of the line. *L1* must have the same number of elements as *L0*.

A named variable that will contain the location of the point on the line between *L0* and *L1* that is closest to *P0*. *Pl* is not necessarily in the interval (*L0, L1*).

If set, and if the point on the line between *L0* and *L1* that is closest to *P0* is not within the interval (*L0, L1*), PNT_LINE will return the distance from *P0* to the closer of the two endpoints *L0* and *L1*.

To print the distance between the point (2,3) and the line from (-3,3) to (5,12), and also the location of the point on the line closest to (2,3), enter the following command:

PRINT, PNT_LINE([2,3], [-3,3], [5,12], Pl), Pl

IDL prints: