LibreVNA/Software/PC_Application/Util/util.h

#ifndef UTILH_H
#define UTILH_H

#include <complex>
#include <math.h>
#include <limits>
#include <vector>

#include <QColor>

namespace Util {
    template<typename T> T Scale(T value, T from_low, T from_high, T to_low, T to_high, bool log_from = false, bool log_to = false) {
        double normalized;
        if(log_from) {
            normalized = log10(value / from_low) / log10(from_high / from_low);
        } else {
            normalized = (value - from_low) / (from_high - from_low);
        }
        if(log_to) {
            value = to_low * pow(10.0, normalized * log10(to_high / to_low));
        } else {
            value = normalized * (to_high - to_low) + to_low;
        }
        return value;
    }

    static inline double SparamTodB(double d) {
        return 20*log10(d);
    }
    static inline double SparamTodB(std::complex<double> d) {
        return SparamTodB(abs(d));
    }
    static inline double SparamToDegree(std::complex<double> d) {
        return (arg(d) * 180.0 / M_PI);
    }
    static inline double SparamToVSWR(double d) {
        if(abs(d) < 1.0) {
            return (1+abs(d)) / (1-abs(d));
        } else {
            return std::numeric_limits<double>::quiet_NaN();
        }
    }
    static inline double SparamToVSWR(std::complex<double> d) {
        return SparamToVSWR(abs(d));
    }
    static inline std::complex<double> SparamToImpedance(std::complex<double> d) {
        return 50.0 * (1.0 + d) / (1.0 - d);
    }
    // all these conversions assume series connection of real and imag part
    static inline double SparamToResistance(std::complex<double> d) {
        return SparamToImpedance(d).real();
    }
    static inline double SparamToCapacitance(std::complex<double> d, double freq) {
        return -1.0 / (SparamToImpedance(d).imag() * 2.0 * M_PI * freq);
    }
    static inline double SparamToInductance(std::complex<double> d, double freq) {
        return SparamToImpedance(d).imag() / (2.0 * M_PI * freq);
    }
    static inline double SparamToQualityFactor(std::complex<double> d) {
        return abs(d.imag()) / d.real();
    }
    // attempts to return a font color with good contrast against the given background color
    static inline QColor getFontColorFromBackground(QColor q) {
        auto brightness = q.redF() * 0.299 + q.greenF() * 0.587 + q.blueF() * 0.114;
        return brightness > 0.6 ? Qt::black : Qt::white;
    }

    void unwrapPhase(std::vector<double> &phase);

    // input values are Y coordinates, assumes evenly spaced linear X values from 0 to input.size() - 1
    void linearRegression(const std::vector<double> &input, double &B_0, double &B_1);
}

#endif // UTILH_H