Data approximation

								
/*  This program demonstrates data approximation upon data
 of the use of Frisian stallions in 1952 - 1982, taken from
 "Het Friese hengstenboek" (E. Dijkstra, Kollum).
 remaining data from Auke Meetsma ...

 The graph shows the decline of the Frisian working-horse
 and the resurrection as a coach-horse.
*/

#include <stdio.h>
#include <math.h>
#include "komplot.h"

int main()
{
 float x[45], xk [4];
 float y[] = {1187,1452,1325,1154,1041,1261,1316,1260,1296,
        1138, 1002,1033,877,804,729,622,596,522,473,411,
        411,446,608,760,735,715,747,823,912,981,
        1019,1128,
        1210, 1308, 1407, 1464, 1586, 1830, 2165, 2389,
        2672, 4433, 3736, 4088, 4401 };
 int i;

 frame_style("cbs");

/* define font = Helvetica (default Times-Roman)*/
 ps_define_font("A", "Helvetica");

 scale_dimensions(0.8);
 tick_distances(1.5, 1.1);
 scale_annotations(1.5);
 format_x_axisnumbers(0,0);
 format_y_axisnumbers(0,0);
 frame(13.5, 1950, 1995, 9.9, 0, 4500, "Year", "", 
 "Nr. of mountings of Frisian stallions");

 for(i=1 ; i < 46 ; i++)
   x[i-1]=1950 + i;

/* line width=0.05 cm, grayvalue = 0 (black) */
 ps_graph_attributes(0.05, 0);
/* mark points with filled circle, isym=17 */
 markers(" ", 45, x, y, 17); 
/* fit a parabola through 5 successive points, 1 times 
*/
 local_parabola_ap("local parabola fitting ", 45,x, y, 1);

 xk[0]=1958;
 xk[1]=1965;
 xk[2]=1972;
 xk[3]=1990;
 line_style_nr(1);

/* skip KOMPLOT warning ...*/
 spline_var_knots_ap("spline with variable knots", 45,x,y,4,xk);
 
 printf (" >>>>>> This program generated KOMPLOT.TMP\n");
 printf (" >>>>>> KOMPLOT.TMP is inputfile for komplot\n");

/*
 komplot(40,"da.ps");
 system("xv da.ps"); 
*/
 return 0;

}