Problems with printing superscripts in a textbox in a graph

Dear colleagues,

I need to write regression results on graphs with several subplots. Texts are prepared in the same loop:

    [c3,r2] = fit(data.P_mm_yr(aaa),data.ET_mm_yr(aaa),f);
    subplot(Nrows,Ncols,i);
    plot(c3,data.P_mm_yr(aaa),data.ET_mm_yr(aaa));
    xlim([0 4000]); ylim([0 4000]);
    paramstxt = cell(3,1);
    paramstxt{1}=num2str(c3.a0,3); 
    paramstxt{2}=num2str(c3.a1,3); 
    paramstxt{3}=num2str(c3.c,3);
    txtE = {strcat('y = ',paramstxt{1},'*x/(1+',paramstxt{2},'*x^{\',paramstxt{3},'}',')')...
        ;strcat('R^2 = ' ,num2str(r2.adjrsquare,2))};
    text(800,3000,txtE);
    legend('off');

However, in some cases text output is OK, e.g., this one:

'y =2.05e+04*x/(1+200*x^{\0.728})'
'R^2 =-0.11'

And in other cases I got the error message:

Warning: Error updating Text.

String scalar or character vector must have valid interpreter syntax:

y =0.925*x/(1+2.82e-07*x^{\2.15})
R^2 =0.33

What is a problem?

Another question: on the graph with regression results (points and regression line) I need also to add a strate line 1:1. How can I do it?

Answer 1

[Cris LaPierre]

Remove the backslash in your exponent.

c3.a0 = 0.925;
c3.a1 = 2.82e-7;
c3.c = 2.15;
r2.adjrsquare = -0.11;

paramstxt = cell(3,1);
paramstxt{1}=num2str(c3.a0,3);
paramstxt{2}=num2str(c3.a1,3);
paramstxt{3}=num2str(c3.c,3);
txtE = {strcat('y = ',paramstxt{1},'*x/(1+',paramstxt{2},'*x^{',paramstxt{3},'}',')')...
    ;strcat('R^2 = ' ,num2str(r2.adjrsquare,2))};
text(800,3000,txtE);
xlim([0 4000]); ylim([0 4000]);

Also, for straight lines, look into xline and yline.

[Fyodor Tatarinov]

Thanks, it works