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Unrecognized function or variable 'delta1'.

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Mia Chan
Mia Chan am 15 Mär. 2023
Kommentiert: Mia Chan am 16 Mär. 2023
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));
  2 Kommentare
Jan am 15 Mär. 2023
Whenever you mention an error in the forum, care for attaching a copy of the complete error message. Then the readers do not have to search or to guess, which line of code is concerned.
Mia Chan
Mia Chan am 16 Mär. 2023
okay, thankyou sir

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Akzeptierte Antwort

Jan am 15 Mär. 2023
Bearbeitet: Jan am 15 Mär. 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 Kommentar
Mia Chan
Mia Chan am 16 Mär. 2023
thankyou very much for your help and the corection of the code, and yes its m1= ones(size(x1));

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Bhanu Prakash
Bhanu Prakash am 15 Mär. 2023
Bearbeitet: Bhanu Prakash am 15 Mär. 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 Kommentar
Mia Chan
Mia Chan am 16 Mär. 2023
Thanks for the explanation, i will try to define it!

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