9.7.5 Fitting sample

C++ code

mglData rnd(100), in(100), res;
rnd.Fill("0.4*rnd+0.1+sin(2*pi*x)", gr->Min, gr->Max);
in.Fill("0.3+sin(2*pi*x)", gr->Min, gr->Max);
gr->Axis(mglPoint(-1,-2), mglPoint(1,2));
gr->Plot(rnd, ". ");
gr->Box();
float ini[3] = {1,1,3};
gr->Fit(res, rnd, "a+b*sin(c*x)", "abc", ini);
gr->Plot(res, "r");
gr->Plot(in, "b");
gr->Text(mglPoint(-1, -1.3), "fitted:", "L:r", -1);
gr->PutsFit(mglPoint(0, -1.8), "y = ", "C:r", -1);
gr->Text(mglPoint(0, 2.2), "initial: y = 0.3+sin(2\\pi x)", "C:b", -1);

MGL code

new rnd 100
fill rnd '0.4*rnd+0.1+sin(2*pi*x)'
new in 100
fill in '0.3+sin(2*pi*x)'
yrange -2 2
plot rnd '. '
box
list ini 1 1 3
fit res rnd 'a+b*sin(c*x)' 'abc' ini
plot res 'r'
plot in 'b'
text -1 -1.3 'fitted:' 'L:r' -1
putsfit 0 -1.8 'y = ' 'C:r'
text 0 2.2 'initial: y = 0.3+sin(2\pi x)' 'C:b' -1

Pure C code

HMDT rnd,in,res;
float ini[3] = {1,1,3};
rnd = mgl_create_data_size(100,1,1);
in = mgl_create_data_size(100,1,1);
res = mgl_create_data();
mgl_data_modify(rnd,"0.4*rnd+0.1+sin(4*pi*x)",0);
mgl_data_modify(in,"0.3+sin(4*pi*x)",0);
mgl_set_axis_2d(gr,-1.,-2.,1.,2.);
mgl_plot(gr,rnd,". ");
mgl_box(gr,1);
mgl_fit_1(gr,res,rnd,"a+b*sin(c*x)","abc",ini);
mgl_plot(gr,res,"r");   mgl_plot(gr,in,"b");
mgl_puts_ext(gr,-1.,-1.3,0.,"fitted:","L:r",-1.,'t');
mgl_puts_fit(gr,0.,-1.8,0.,"y = ","C:r",-1.);
mgl_puts_ext(gr,0.,2.2,0.,"initial: y = 0.3+sin(2\\pi x)","C:b", -1., 't');

Fortran code

integer rnd,in,res, mgl_create_data_size
real ini(3)
ini(1)=1;   ini(2)=1;   ini(3)=3;
rnd = mgl_create_data_size(100,1,1);
in = mgl_create_data_size(100,1,1);
res = mgl_create_data();
call mgl_data_modify(rnd,"0.4*rnd+0.1+sin(4*pi*x)",0);
call mgl_data_modify(in,"0.3+sin(4*pi*x)",0);
call mgl_set_axis_2d(gr,-1.,-2.,1.,2.);
call mgl_plot(gr,rnd,". ");
call mgl_box(gr,1);
call mgl_fit_1(gr,res,rnd,"a+b*sin(c*x)","abc",ini);
call mgl_plot(gr,res,"r");
call mgl_plot(gr,in,"b");
call mgl_puts_ext(gr,-1.,-1.3,0.,"fitted:","L:r",-1.,'t');
call mgl_puts_fit(gr,0.,-1.8,0.,"y = ","C:r",-1.);
call mgl_puts_ext(gr,0.,2.2,0.,"initial: y = 0.3+sin(2\\pi x)","C:b", -1., 't');

Python

rnd, In, res, ini = mglData(100), mglData(100), mglData(), mglData(3);
rnd.Modify("0.4*rnd+0.1+sin(4*pi*x)");
In.Modify("0.3+sin(4*pi*x)");
gr.SetRanges(-1,1,-2,2);
gr.Plot(rnd,". ");
gr.Box();
ini[0], ini[1], ini[2] = 1, 1, 3;
gr.Fit(res,rnd,"a+b*sin(c*x)","abc",ini);
gr.Plot(res,"r");   gr.Plot(In,"b");
gr.Puts(-1,-1.3,0,"fitted:","L:r",-1);
gr.PutsFit(0,-1.8,0,"y = ","C:r",-1);
gr.Puts(0,2.2,0,"initial: y = 0.3+sin(2\\pi x)","C:b",-1);