Unrecognized function or variable 'delta1'.

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Hello! Whenever I run the following code, the error Unrecognized function or variable 'delta1' appears. Anyone who can help me I would be very grateful.
clear all;
%ccd to sorce = 17 cm
% ccd to object = 2 cm
% object to source = 15 cm
% size of image pixel and dimension
N = 423;%input ('Size Pixel NxN pixel=');
% M = 736;
L = N*7.00e-6/2;
wvl = 0.650e-6;
k = 2*pi/wvl;
%Dz = 0.03;
awal = 0; %input ('initial position (m) = ');
batas = 0.025; % input ('batas jarak rekontruksi (m) dari 0 ~ ');
%---------------Loop to create images
step = 0.0005;%input ('step size (m) = ');
for Dz=awal:+step:batas
[x1, y1]=meshgrid((-N/2:N/2-1)*delta1);
[data] = imread('jojo.jpg');
datared = data (1:N,1:N, 1);
%array refrence wave
kx = k*x1/Dz;
ky = k*y1/Dz;
%dataf = double(datared)-mean2(double(datared));
%dataf = double(max(max(datared)))-double(datared);
%dataf = exp (-1i*k*Dz*double(datared));%-mean2(datared);
%dataf = exp (-2*pi*1i.*(kx+ky).*double(datared));
dataf = double(datared);
r=sqrt(0.17^2*m1 + x1.*xq+y1.*y1);
%Uref = exp (1i*2*pi)./r;
%Uref = 2*pi/wvl;
%lensa = exp
lensa = exp(-1i*k*Dz-(1i*k* (x1.*x1+ y1.*y1)/1i*k*Dz)); % (2*0.02));
filter = exp(-2*pi*1i.*(kx*0.02+ky*0.02));
%datai= dataf. *Uref;
datai = dataf; %.*filter;
[Uot] = fresnel3 (datai, L, wvl, Dz);
reall = Uout.*Uout;
imaginary = imag (Uout.*Uout);
%datao = imag (Uout);
%datao = real (reall) + imaginary;
%datao = atan (imag (Uout)./real (Uout));
datao = abs (Uout).*abs (Uout);
%datao= real (Uout. *Uout) +imag (Uout. *Uout);
%imshow (uint8 (200*datao/max (max (datao))));
imagesc ((uint8 (200*datao/max (max (datao))))), colormap (gray); axis equal; axis tight; ylabel('pixels');
xlabel(['Nilai Dz =',num2str(Dz),'m']);
title(' Image reconstructed by Fresnell Transform ')
%imwrite (uint8 (200*datao/max (max (datao))), sprintf( 'benang_%02d.jpg', Dz));
imwrite (uint8 (200*datao/max (max (datao))), sprintf( 'ini_real_%02d.jpg', Dz ));
disp('Press any key to continue... ');
function [u2] = fresnel (u1, L, lambda, ~)
[M,~] = size (u1);
dx = L/M;
k = 2*pi/lambda;
fx = -1/(2*dx): 1/L:1/(2* dx)-1/L;
[FX, FY] = meshgrid(fx, fx);
H = exp(-i*pi* lambda*z* (FX.^2 + FY.^2));
H = fftshift (H);
U1 = fft2(fftshift (u1));
U2 = H.*U1;
u2 = ifftshift (ifft2 (U2));

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Accepted Answer

Jan on 15 Mar 2023
Edited: Jan on 15 Mar 2023
Exactly as the error message tells you: The variables or function "delta1" is not defined. Then this linemust fail:
[x1, y1]=meshgrid((-N/2:N/2-1)*delta1);
Fix this by defining delta1.
By the way, what is "one()" and "sixe()"?
Do you mean:
m1 = ones(size(x1));
  1 Comment
Mia Chan
Mia Chan on 16 Mar 2023
thankyou very much for your help and the corection of the code, and yes its m1= ones(size(x1));

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More Answers (1)

Bhanu Prakash
Bhanu Prakash on 15 Mar 2023
Edited: Bhanu Prakash on 15 Mar 2023
Hi Mia,
As per my understanding, you are facing an error while running your code.
The reason is that “MATLAB” does not recognize the specified term “delta1” as the name of a function on the “MATLAB” path or as a variable.
This error usually occurs when the variable/function has not been defined before the execution reaches it’s instance.
Please look at the code below, for your reference:
>> a=1;
>> b=2;
>> d=a+b+c;
Unrecognized function or variable 'c'.
In the above code, “c” is not declared but it is used to compute “d”. This throws an error.
This error can be avoided by defining “c” before computing “d”:
>> a=1;
>> b=2;
>> c=3;
>> d=a+b+c
d =
See this documentation for more tips:
Hope this answer helps you.
Bhanu Prakash.
  1 Comment
Mia Chan
Mia Chan on 16 Mar 2023
Thanks for the explanation, i will try to define it!

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