Fitting.en

>A:=[1,2;3,4]; b:=[5;6]; A\b
           -4 
          4.5 
>A:=normal(200,200); b:=sum(A); longest totalmax(abs(inv(A).b-1))
 5.158096172408477e-013 
>A:=redim(1:9,3,3); det(A)
0
>b:=[1,2,4]'; x:=fit(A,b); fraction(x)
      1/6 
      1/3 
        0 
>fraction(A.x-b)
     -1/6 
      1/3 
     -1/6 
% polyfit, polyval
>x:=[1:10]; y:=[5.7,6.5,6.7,6.4,7.7,7,8.6,9.3,9.3,13.2]; plot2d(x,y,>points); 
>for i = 1 to 3; p:=polyfit(x,y,i); plot2d("polyval(p,x)",color=i+3,>add); end;
% modelfit (1. Beispiel)
>function fexp(x,[a,b,c]):=a*x+b*exp(c*x)
>p:=modelfit("fexp",[1,10,-1],x,y)
[1.12129,  6.76896,  -0.292959]
>plot2d(x,y,>points); plot2d("fexp(x,p)",>add):
 %image% Fitting-001.png
% modelfit (2. Beispiel)
>function model(x,p) := p[1]*cos(p[2]*x)+p[2]*sin(p[1]*x);
>xdata = [-2,-1.64,-1.33,-0.7,0,0.45,1.2,1.64,2.32,2.9];
>ydata = [0.699369,0.700462,0.695354,1.03905,1.97389,2.41143, ...
>1.91091,0.919576,-0.730975,-1.42001];
>p:=modelfit("model",[1.5,0.5],xdata,ydata)
[1.88185,  0.70023]
>plot2d(xdata,ydata,>points); plot2d("model(x,p)",>add):
 %image% Fitting-002.png
>