Determining lengths of vector lines

[James Darrell McCauley]

ng240 at ursus.pnl.gov (ng240 at ursus.pnl.gov) writes on 10 Feb 94:
>Does anyone know how to measure the length of a line in a vector file?

I've modified d.what.vect to do this (seems logical since it
already calculates areas). If these seems like something 
that folks my want in 4.2, be sure that this diff gets to 
the right person.

--Darrell

James Darrell McCauley, Purdue Univ, West Lafayette, IN 47907-1146, USA
mccauley at ecn.purdue.edu, mccauley%ecn at purccvm.bitnet, pur-ee!mccauley
** will finish PhD/engr in 9/94 - need job. inquiries welcome (no hh, plz) **

(Rhett: these are the mods that I told you about. only 10 lines). 

% pwd
/tmp_mnt/net/soils7/aggrass/grass4.1/src.other/darrell/d.what.vect/cmd
% diff what.c what.c.orig
1d0
< #include <math.h>
25,26d23
<       struct line_pnts *points;
<       int i;
39d35
<         points = Vect_new_line_struct();
94,99d89
< 
<                       V2_read_line (Map, points, line);
<                       for(i=0,sq_meters=0.0; i<points->n_points-1; i++)
<                               sq_meters += hypot(points->x[i]-points->x[i+1], 
<                                               points->y[i]-points->y[i+1]);
<                       printf("Length - Meters: %.3lf\n",sq_meters);

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