function VHDLSpline()
close all
    x=[50; 150; 250; 350];
    y=[-1845; -456; 1277; 2047];
    
    h0=x(2) - x(1);
    h1=x(3) - x(2);
    h2=x(4) - x(3);
    
    d0=(y(2) - y(1)) / (x(2) - x(1));
    d1=(y(3) - y(2)) / (x(3) - x(2));
    d2=(y(4) - y(3)) / (x(4) - x(3));
    
    g1= 6*d1 - 6*d0;
    g2= 6*d2 - 6*d1;
    %g1=(3/h1)*(y(3)-y(2)) - (3/h0)*(y(2)-y(1)); %schlechter
    %g2=(3/h2)*(y(4)-y(3)) - (3/h1)*(y(3)-y(2)); %schlechter
    
    s = Gauss(h0, h1, h2, g1, g2);
    
    a=y(1);
    b=d1 - (h1/6)*(s(2)+(2*s(1)));
    c=s(1)/2;
    d=(s(2)-s(1))/(6*h1);
    
    %a=y(1); %schlechter
    %b=(1/h1)*(y(3)-y(2))-(h1/3)*(2*s(1)+s(2)); %schlechter
    %c=g1; %schlechter
    %d=(s(2)-s(1))/(3*h1); %schlechter
    
    coef=[a, b, c, d];
    
    res = a + b*(175) + c*(175)^2 + d*(175)^3;
    fprintf('res=%.6e\n',res);
    fprintf('coef=%.6e\n',coef);
end

function f=Gauss(h0, h1, h2, g1, g2)
    lo=2*(h0+h1);
    ru=2*(h1+h2);
    lu=h1;
    ro=h1;
    
    mult=lo/lu;
    
    ro=ro-(mult*ru);
    g=g1-(mult*g2);
    
    s2=g/ro;
    s1=(g2-(s2*ru))/lu;
    
    f=[s1, s2];
end

function f=Cramer(h0, h1, h2, g1, g2)
    det=(2*(h0+h1))*(2*(h1+h2)) - h1*h1;
    det1=g1*(2*(h1+h2)) - g2*h1;
    det2=(2*(h0+h1))*g2 - h1*g1;
    
    s1=det1/det;
    s2=det2/det;
    
    f=[s1, s2];
end