mnk

lab3.cpp

#include <iostream>
#include <cstdint>
#include <cmath>
#include <vector>

const std::vector<float> xs = {129.0f, 240.0f, 341.0f, 434.0f, 527.0f, 618.0f};
const std::vector<float> ys = {5939.0f, 7634.0f, 10986.0f, 13862.0f, 16094.0f, 17917.0f};
const uint32_t n = 6;

static std::vector<float>
ABCD()
{
    float A, B, C, D;
    A = B = C = D = 0.0f;

    for (uint32_t i = 0; i < n; ++i)
    {
        float x_i = xs[i], y_i = ys[i];
        A += x_i * x_i;
        B += x_i;
        C += x_i * y_i;
        D += y_i;
    }

    return {A, B, C, D};
}

static std::vector<float>
MNK()
{
    auto abcd = ABCD();
    float a = (abcd[2] * n - abcd[3] * abcd[1]) / (n * abcd[0] - abcd[1] * abcd[1]);
    float b = (abcd[3] - a * abcd[1]) / n;
    return {a, b};
}

void
MNK9()
{
    /*
    float x_0 = xs[0], x_n = xs[n - 1];
    float y_0 = ys[0], y_n = ys[n - 1];

    float x_a = (x_0 + x_n) / 2.0f;
    float y_a = (y_0 + y_n) / 2.0f;
    float x_g = std::sqrt(x_0 * x_n);
    float y_g = std::sqrt(y_0 * y_n);
    float x_h = (2 * x_0 * x_n) / (x_0 + x_n);
    float y_h = (2 * y_0 * y_n) / (y_0 + y_n);
    */

    std::vector<float> delta =
    {
        std::abs(373.5f - 11928.0f),
        std::abs(282.351f - 10315.5f),
        std::abs(373.5f - 10315.5f),
        std::abs(252.351 - 11928.0f),
        std::abs(213.446f - 11928.0f),
        std::abs(373.5f - 8920.95f),
        std::abs(213.446f - 8920.95f),
        std::abs(213.446f - 10315.5f),
        std::abs(282.351f - 8920.95f)
    };

    float delta_min = delta[0];
    uint32_t min_i = 0;

    for (uint32_t i = 1; i < delta.size(); ++i)
    {
        if (delta[i] < delta_min)
        {
            delta_min = delta[i];
            min_i = i;
        }
    }

    ++min_i;
    auto ab = MNK();

    switch (min_i)
    {
        case 1:
        {
            std::cout << "Using y = a*x + b" << std::endl;
            std::cout << "a = " << ab[0] << std::endl
            << "b = " << ab[1] << std::endl;
            break;
        }
        case 2:
        {
            std::cout << "Using y = a*x^b" << std::endl;
            break;
        }
        case 3:
        {
            std::cout << "Using y = a*e^(bx)" << std::endl;
            break;
        }
        case 4:
        {
            std::cout << "Using y = a*ln(x) + b" << std::endl;
            break;
        }
        case 5:
        {
            std::cout << "Using y = a/x + b" << std::endl;
            break;
        }
        case 6:
        {
            std::cout << "Using y = 1/(ax + b)" << std::endl;
            break;
        }
        case 7:
        {
            std::cout << "Using y = x(ax + b)" << std::endl;
            break;
        }
        case 8:
        {
            std::cout << "Using y = a*e^(b/x)" << std::endl;
            break;
        }
        case 9:
        {
            std::cout << "Using y = 1/(a*ln(x) + b)" << std::endl;
            break;
        }
    }
}

int32_t
main(void)
{
    // auto ab = MNK();
    // std::cout << ab[0] << " " << ab[1] << std::endl;

    MNK9();

    return(0);
}