ngspice/src/frontend/points.c

/**********
Copyright 1990 Regents of the University of California.  All rights reserved.
Author: 1985 Wayne A. Christopher, U. C. Berkeley CAD Group 
**********/

#include <ngspice.h>
#include <cpdefs.h>
#include <ftedefs.h>
#include <dvec.h>
#include <graph.h>
#include <ftedbgra.h>

#include "points.h"


/* Returns the minimum and maximum values of a dvec. Returns a pointer
 * to static data.  If real is TRUE look at the real parts, otherwise
 * the imag parts.  */



double *
ft_minmax(struct dvec *v, bool real)
{
    static double res[2];
    register int i;
    double d;

    res[0] = HUGE;
    res[1] = - res[0];

    for (i = 0; i < v->v_length; i++) {
        if (isreal(v))
            d = v->v_realdata[i];
        else if (real)
            d = realpart(&v->v_compdata[i]);
        else
            d = imagpart(&v->v_compdata[i]);
        if (d < res[0])
            res[0] = d;
        if (d > res[1])
            res[1] = d;
    }
    return (res);
}

/* Figure out where a point should go, given the limits of the plotting
 * area and the type of scale (log or linear).
 */

int
ft_findpoint(double pt, double *lims, int maxp, int minp, bool islog)
{
    double tl, th;

    if (pt < lims[0])
        pt = lims[0];
    if (pt > lims[1])
        pt = lims[1];
    if (islog) {
        tl = mylog10(lims[0]);
        th = mylog10(lims[1]);
        return (((mylog10(pt) - tl) / (th - tl)) *
                (maxp - minp) + minp);
    } else {
        return (((pt - lims[0]) / (lims[1] - lims[0])) *
                (maxp - minp) + minp);
    }
}

/* Will report the minimum and maximum in "reflection coefficient" space
 */

double *
ft_SMITHminmax(struct dvec *v, bool yval)
{
    static double res[2];
    register int i;
    double d, d2;

    res[0] = HUGE;
    res[1] = - res[0];

    for (i = 0; i < v->v_length; i++) {
        if (isreal(v))
	    SMITH_tfm( v->v_realdata[i], 0.0, &d, &d2 );
	else
            SMITH_tfm( realpart(&v->v_compdata[i]), imagpart(&v->v_compdata[i]),
								&d, &d2 );
/* Are we are looking for min/max X or Y ralue
 */
	if( yval )
		d = d2;

        if (d < res[0])
            res[0] = d;
        if (d > res[1])
            res[1] = d;
    }
    return (res);
}

int
SMITH_tfm(double re, double im, double *x, double *y)
{
	double	dnom;

	dnom = (re + 1) * (re + 1) + im * im;
	*x = (re * re + im * im - 1) / dnom;
	*y = 2 * im / dnom;

	return 0;
}