problem with dealing images with formulas

i want to display the results in an axes. i1 i2 i3 i4 i5 i6 are images displayed on individual axes and i want to display a final result which will only display 1 image "diff".

theta = 0.5 * arctan ((i5 - i3) / (i4 - i6));
delta = arctan( 2 * (i5 - i4) / (i1 - i2)*(sin2(theta) - cos2(theta)));
N = delta / (2*3.14);
fsigma = ((8 * 200) / (3.14 * 22.5 * 7));
diff = (N * fsigma) / 22.5;

axes(handles.axes14)
imagesc(abs(diff)),title('Stress distribution in the bone'),xlabel('Pixel'),ylabel('Pixel'),colorbar;

but it gives me these errors:

??? Error using ==> mrdivide
Linear algebra is not supported for integer data types.

Error in ==> VPPP>calButton_Callback at 208
theta = 0.5 * arctan ((i5 - i3) / (i4 - i6));

Error in ==> gui_mainfcn at 96
        feval(varargin{:});

Error in ==> VPPP at 42
    gui_mainfcn(gui_State, varargin{:});

Error in ==>
@(hObject,eventdata)VPPP('calButton_Callback',hObject,eventdata,guidata(hObject))

??? Error while evaluating uicontrol Callback

I'm not sure what has gone wrong.

Answer 1

[Walter Roberson]

Are you sure you want matrix division and not element-by-element division which is the ./ operator ?

Anyhow, you should probably be using double() of the images when you are doing numeric calculations.

Note: it is not recommended that you call any variable "diff" as that will interfere with the use of the diff() function.

[joanna]

How do i use the ./ operator?

[Walter Roberson]

For example, change

theta = 0.5 * arctan ((i5 - i3) / (i4 - i6));

to

theta = 0.5 * arctan ((i5 - i3) ./ (i4 - i6));