quit program using if

hi, i create a program:

% optimal algorithm
clear all
close all
%%Insert value in Matlab
dlg_title = 'Insert Factor Value';
x1 = inputdlg('Enter number of channels:',dlg_title, [1 50]);
n = str2num(x1{:});
x2 = inputdlg('Enter input power for each channel (mW):',dlg_title, [1 50]);
p = str2num(x2{:})*10^-3;
x3 = inputdlg('Enter channel spacing (nm):',dlg_title, [1 50]);
delta_lambda = str2num(x3{:})*10^-9;
x4 = inputdlg('Enter distance transmission (km):',dlg_title, [1 50]);
distance = str2num(x4{:});
CreateStruct.Interpreter = 'tex';
CreateStruct.WindowStyle = 'modal';
choice = menu('Choose optical fiber type','Single-mode fiber ( G.652 )','Dispersion-shifted fiber ( G.653 )','Non-zero dispersion-shifted fiber ( G.655 )');
if choice==1
    alphadb = 0.20;
    dispersion=16;
    slope=0.080;
    A=80;
    recommend=sprintf('Single-mode fiber ( G.652 ) is not suitable for this situation');
elseif choice==2
    alphadb = 0.22;
    dispersion=0.001;
    slope=0.075;
    A=50;
    recommend=sprintf('Dispersion-shifted fiber ( G.653 ) is not suitable for this situation');
else
    alphadb = 0.23;
    dispersion=3;
    slope=0.050;
    A=72; 
    recommend=sprintf('Non-zero dispersion-shifted fiber ( G.655 ) is not suitable for this situation');
end

B=2.5

i also have some code below

now if the: distance > 104000/(B^2*dispersion) , i want to DISPLAY a message box: "distance is not good. try again" and QUIT the program, else the program CONTINUES .

Answer 1

[Image Analyst]

Try this:

maxAllowedValue = 104000/(B^2*dispersion) ;
if distance > maxAllowedValue
  message = sprintf('Distance of %s is greater than the max allowed value of %f.\nPlease try again.', distance, maxAllowedValue);
  uiwait(warndlg(message));
  return;  % Would be nicer to user to use a while loop rather than exit the program.
end

[son]

i have use:'return' but the program doesn;t start again?

[Image Analyst]

That's right. Because you asked that it " QUIT the program", so I did exactly what you asked for. I presume you were going to have your use manually restart the program, that's why my comment said it would be nicer to the user to have that part in a while loop instead of calling return to quit the program.