Input Argument for contour must be real

I have an error in contourf function : "Input arguments for contour must be real. Use the function REAL to get the real part of the inputs."

I've checked the input file ,the data are all real numbers. Here's the code.

Thanks for your help .

[Walter Roberson]

Copyrighted Mathworks code removed.

What we need is a copy of all of the inputs you are passing to contour(). Put them into a .mat file and attach that, and also show us the command you are using.

[maria pigiaki]

Copyrighted Mathworks code didnt remove, i just didint copied that part. My mistake,sorry.

This is what you aske for. Appreciate your help muchly.

%% this concludes the data Xtraction, what follows is Graphs and saVes
%%
%% plOt main fiG ??
if ((~isempty(A_Files))&&(~isempty(B_Files)))
    if lpot_questionMark == 'y'

        f( 1 ) = figure( 1 );
        set(gca,'LooseInset',get(gca,'TightInset'));

        colormap jet
        contourf( X,Y, real( OD_MO), linspace( min(min(OD_MO)), max( max( OD_MO) ),40 ),'EdgeColor' , 'none' ); 
        title( 'OD full formula' ); xlabel( 'Time (ps)' ); ylabel( 'Wavelength (nm)' );
        caxis([color_min, color_max])
        colorbar
        movegui( f( 1 ), 'east' )
        if save_questionMark == 'y';
            img=[ saVe_path, 'OD', '_', Date, '_' , Numb, '.png' ]; % 
            saveas( f( 1 )  , img ); clear img
            ReCreatedAtA_n_ShAVe_Asc_mAnimal( X,Y, real( OD_MO ), saVe_path , strcat('OD_Formulargh', '_', Date, '_' , Numb) )        
        else
        end
    else
    end
end

[Walter Roberson]

 contourf( X,Y, real( OD_MO), linspace( min(min(OD_MO)), max( max( OD_MO) ),40 ),'EdgeColor' , 'none' );

That tells us that you expect OD_MO to have complex values, as otherwise you would not real() it. But what are min() and max() of complex values? Can you guarantee that if you take min() of a complex number that the result is real valued?

[maria pigiaki]

No i cant guarantee that of course.

I just want to select the real part of the complex number to plot my 2D graph.

Answer 1

[Walter Roberson]

rOD = real(OD_MO(:));        
minOD = min(rOD);
maxOD = max(rOD);
contourf( X,Y, real( OD_MO), linspace( minOD, maxOD, 40), 'EdgeColor' , 'none' ); 

[maria pigiaki]

I tried what u proposed. Didnt solve the problem .

I think the problem is that the imaginary part of the complex numbers are not saved.Here's the path that saves to an ascii file the img part.

function ReCreatedAtA_n_ShAVe_Asc( time , lamba , intensity , path , datae , nameXtension , measurementNo )
% %  ReCreatedAtA_n_ShAVe_Asc
% % ReCreates form ov initial dAtA mAtRix by concatenation   & shAVe iT

intensity_ = cat( 1 , time.' , intensity );
lamba_ = cat ( 1 , 0 , lamba );
mutation = cat( 2 , lamba_ , intensity_ );
nombre = strcat( path , '2D_AB_' , datae , '_0' , measurementNo , '_' , nameXtension , '.asc' );
save( nombre , 'mutation' , '-ascii' , '-tabs' );

disp( strcat( 'Saved asc file @ '  , path ) );
end

[Walter Roberson]

rOD = real(OD_MO(:));
rOD(~isfinite(rOD)) = nan;   %zap +/- inf
minOD = min(rOD);
maxOD = max(rOD);
contourf( X,Y, reshape(rOD,size(OD_MO)), linspace( minOD, maxOD, 40), 'EdgeColor' , 'none' ); 

This will not be very interesting, because the majority of the variation is along x approximately 300.

[Walter Roberson]

Whether or not imaginary portions are saved has nothing to do with the problem you reported about contourf saying that the inputs must be real.

[maria pigiaki]

ok,thank you very much