# Example 3 -- interpolated smoothing functions

```#include <stdio.h>
#include <ncarg/ncargC.h>
#include <ncarg/gks.h>
#include <ncarg/ngmath.h>

void c_drwft3(float, float, int, float [], float [],
int, float [], float [], float []);
void c_bkgft3(float, float, float, char *, float, float, float);

/*
*  Example of curvs, curvps.
*/

#define IDIM  10
#define IOUT 201

#define IWTYPE 1
#define WKID   1

main()
{
float x[] = { 0.000, 0.210, 0.360, 0.540, 1.000,
1.500, 1.970, 2.300, 2.500, 2.700};
float y[] = { 0.000, 2.600, 3.000, 2.500, 0.000,
-1.000, 0.000, 0.800, 0.920, 0.700};
float xinc, xo[IOUT], yos[IOUT], yosp[IOUT];
float p = 3., d, xr = 5., xl = -1.;
int   i;

/*
*  Create the output X coordinate array.
*/
xinc =  (xr-xl)/(IOUT-1);
for (i = 0; i < IOUT; i++) {
xo[i] = xl + xinc*i;
}

/*
*  Calculate the interpolated values.
*/
d = 0.3;
c_ftcurvs(IDIM, x, y, 1, &d, IOUT, xo, yos);
/*
*  Calculate the interpolated values for a periodic function.
*/
c_ftcurvps(IDIM, x, y, p, 1, &d, IOUT, xo, yosp);

/*
*  Draw plot.
*/
c_drwft3(xl, xr, IDIM, x, y, IOUT, xo, yos, yosp);

}
void c_drwft3(float xl, float xr, int n, float x[], float y[],
int m, float xo[], float yos[], float yosp[])
{

float ypos_top = 0.95, yb, yt;
int   i;

Gcolr_rep rgb;
Gpoint plist[IDIM];
Gpoint_list pmk;

/*
*  Open GKS, open and activate a workstation.
*/
gopen_gks("stdout",0);
gopen_ws(WKID, NULL, IWTYPE);
gactivate_ws(WKID);

/*
* Define a color table.
*/
rgb.rgb.red = rgb.rgb.green = rgb.rgb.blue = 1.;
gset_colr_rep(WKID,0,&rgb);
rgb.rgb.red = rgb.rgb.green = rgb.rgb.blue = 0.;
gset_colr_rep(WKID,1,&rgb);
rgb.rgb.red = 1.;
rgb.rgb.green = rgb.rgb.blue = 0.;
gset_colr_rep(WKID,2,&rgb);
rgb.rgb.red = rgb.rgb.green = 0.;
rgb.rgb.blue = 1.;
gset_colr_rep(WKID,3,&rgb);

gset_clip_ind(1);

/*
* Graph the interpolated function values and mark the original
* input data points.
*/
yb = -2.0;
yt =  4.0;
c_bkgft3(xl,xr,ypos_top,"c_curvs",0.4,yb,yt);
c_gridal(6,5,3,1,1,1,10,xl,yb);
c_curve(xo,yos,m);

/*
*  Mark the input data points.
*/
for (i = 0; i < n; i++) {
plist[i].x = x[i];
plist[i].y = y[i];
}
gset_marker_size(2.);
gset_marker_colr_ind(3);
pmk.num_points = n;
pmk.points = plist;
gpolymarker(&pmk);

/*
*  Graph the periodic function.
*/
c_bkgft3(xl,xr,ypos_top-0.47,"c_curvps",0.4,yb,yt);
c_gridal(6,5,3,1,1,1,10,xl,yb);
c_curve(xo,yosp,m);

/*
*  Mark the input data points.
*/
for (i = 0; i < n; i++) {
plist[i].x = x[i];
plist[i].y = y[i];
}
gset_marker_size(2.);
gset_marker_colr_ind(3);
pmk.num_points = n;
pmk.points = plist;
gpolymarker(&pmk);
c_frame();

/*
*  Deactivate and close workstation, close GKS.
*/
gdeactivate_ws(WKID);
gclose_ws(WKID);
gclose_gks();
}

void c_bkgft3(float xleft, float xright, float ypos, char *label,
float xlp, float yb, float yt) {
c_set(0.,1.,0.,1.,0.,1.,0.,1.,1);
c_pcseti("fn",21);
c_plchhq(xlp,ypos-0.03,label,0.035,0.,-1.0);
c_set(0.13,0.93,ypos-0.35,ypos,xleft,xright, yb, yt, 1);
gset_line_colr_ind(2);
c_line(xleft, 0., xright, 0.);
c_sflush();
gset_line_colr_ind(1);
c_gaseti("lty",1);
c_pcseti("fn",21);
c_gasetr("xls",0.02);
c_gasetc("xlf","(f4.1)");
c_gasetr("yls",0.02);
c_gasetc("ylf","(f5.2)");
c_gasetr("xmj",0.02);
c_gasetr("ymj",0.02);
}
```

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