MATLAB: How to fix “Undefined function ‘sinc’ for input arguments of type ‘double’.” Error

Question

I found a code to use for my project far field diffraction generator however, I got an error called, Undefined function 'sinc' for input arguments of type 'double'.

How can i fix this?

Here is my code:

%------------------------------------------------------------------------




%-----Fraunhofer diffraction from a rectangular aperture-----------------
%------------------------------------------------------------------------
clc
close all
clear all
%------------------------------------------------------------------------
lambda=500e-9; k=(2*pi)/lambda; % wavelength of light in vaccuum
a=1e-6; b=1e-6; % dimensions of diffracting rectangular aperture
                % a is along Z and b is along Y
Io=100.0; % relative intensity
R=1.0e-3; % distance of screen from aperture
Y=(-0.25e-2:1e-5:0.25e-2); Z=Y ; % coordinates of screen
beta=k*b*Y/(2*R*pi);alpha=k*a*Z./(2*R*pi); % intermediate variable
 % diffracted intensity
for i=1:length(Y)
    for j=1:length(Z)
I(i,j)=Io.*((sinc(alpha(j)).^2).*(sinc(beta(i))).^2);
    end
end
%------------------------------------------------------------------------
   
 figure(1)
 imshow(I)
 title('Fraunhofer Diffraction','fontsize',14)
 fh = figure(1);
 set(fh, 'color', 'white'); 
 
 %------------------------------------------------------------------------

Answer 1

I didnot find any error, when I run the code in my system (2015b)

clc;
clear all;
close all;
lambda=500e-9; k=(2*pi)/lambda; % wavelength of light in vaccuum
a=1e-6; b=1e-6; % dimensions of diffracting rectangular aperture
                % a is along Z and b is along Y
Io=100.0; % relative intensity
R=1.0e-3; % distance of screen from aperture
Y=(-0.25e-2:1e-5:0.25e-2); Z=Y ; % coordinates of screen
beta=k*b*Y/(2*R*pi);alpha=k*a*Z./(2*R*pi); % intermediate variable
 % diffracted intensity
for i=1:length(Y)
    for j=1:length(Z)
I(i,j)=Io.*((sinc(alpha(j)).^2).*(sinc(beta(i))).^2);
    end
end
%------------------------------------------------------------------------

 figure(1)
 imshow(I)
 title('Fraunhofer Diffraction','fontsize',14)
 fh = figure(1);
 set(fh, 'color', 'white'); 
 
 %------------------------------------------------------------------------