how to write data from a loop to excel file

Io=0.86;

Iv=0.43;

for theta= 0:6:360

    Imax = Io+Iv+2*cos (theta)*sqrt(Io.*Iv);
    Imin = Io+Iv-2*cos (theta)*sqrt(Io.*Iv);
    fringe_contrast =(Imax-Imin)/(Imax+Imin);

 end

how do i store the values of theta, Imax, Imin and fringe_contrast in an excel file to show all the values generated from the loop?

Answer 1

[bio lim]

Io=0.86;
Iv=0.43;

theta = 0:6:360; % Better use vectorization
Imax = Io+Iv+2*cos(theta) * sqrt(Io.*Iv);
Imin = Io+Iv-2*cos(theta) * sqrt(Io.*Iv);
fringe_contrast = (Imax-Imin)./(Imax+Imin); % Element-wise division

filename = 'data.xlsx';
A = {'theta','Imax','Imin','fringe_contrast'; theta.', Imax.', Imin.', fringe_contrast.'};
sheet = 1;
xlRange = 'B1';
xlswrite(filename, A, sheet, xlRange)

I don't have MATLAB installed for the laptop I am using right now, so I cannot check right now. Tell me if there is any problem.

[Sid]

Added a couple of tweaks to coffee's original answer.

Io=0.86;
Iv=0.43;
theta = [0:6:360]; % Better use vectorization
Imax = Io+Iv+2*cos (theta)*sqrt(Io.*Iv);
Imin = Io+Iv-2*cos (theta)*sqrt(Io.*Iv);
fringe_contrast =(Imax-Imin)./(Imax+Imin); % Element-wise division
%
%   A = {'theta','Imax','Imin','fringe_contrast'; theta.', Imax.', Imin.', fringe_contrast.'};
%
% Write the table headers. Kept it separately in case you want to use different headers.
tableHeaders =  {'theta','Imax','Imin','fringe_contrast' };
%
% Export out using xlswrite.
filename = 'data.xlsx';
sheet = 1;
xlRange = 'A1';
xlswrite(filename, tableHeaders, sheet, xlRange)
%
% Main Array to report.
mainArrayToWrite = [theta.', Imax.', Imin.', fringe_contrast.'];
%
% Export Main Array to the same file.
filename = 'data.xlsx';
sheet = 1;
xlRange = 'A2';
xlswrite(filename, mainArrayToWrite, sheet, xlRange)

Kept the main array and the table headers separately in case you want to add different names, etc.

HTH.

[alex kariuki]

Thanks alot for your comments

The code you provided only writes headers to the excel file, what i was actually interested in is the for-loop. As you can see, Imax and Imin values change as i perform cos of theta (theta is angles from 0 to 360 insteps of 6 degrees).

I want to write the values of the Imax, Imin, and fringe_contrast in an excel file according to the different values of theta.

That's why i included a for-loop, may be you didn't see the loop in my question.

[bio lim]

Hi Alex. Try Sid's nice corrected version.

Io=0.86;
Iv=0.43;
theta = 0:6:360; % Better use vectorization
Imax = Io+Iv+2*cos(theta) * sqrt(Io.*Iv);
Imin = Io+Iv-2*cos(theta) * sqrt(Io.*Iv);
fringe_contrast =(Imax-Imin)./(Imax+Imin); 
tableHeaders =  {'theta','Imax','Imin','fringe_contrast' };

filename = 'data.xlsx';
sheet = 1;
xlRange = 'A1';
xlswrite(filename, tableHeaders, sheet, xlRange)

 mainArrayToWrite = [theta.', Imax.', Imin.', fringe_contrast.'];

 filename = 'data.xlsx';
sheet = 1;
 xlRange = 'A2';
 xlswrite(filename, mainArrayToWrite, sheet, xlRange)

Using loop is often not ideal, because they take longer than vectorization. Checked it and it works. HTH