plot the graph of function

Question

shiv gaur 2022-1-29

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1638635-plot-the-graph-of-function

评论： Walter Roberson 2022-1-31

采纳的回答： Kevin Hanekom

l=633;

k0=2*pi/l;

ea=1.39;

da=1:300;

theta=1:70;

y=zeros(length(theta),length(da));

np=1.5;

x=(2*pi/l)*np*sind(theta);

for i=1:length(theta)

for j=1:length(da)

ka=k0*sqrt(ea-x.^2);

f=(1-exp(2*1i.*da(j).*ka(i)))/(1+exp(2*1i.*da(j).*ka(i)));

%pfms=2*atan(1i*a.*b);

y(i,j)=2*atan(1i*c.*f);

disp(y)

end

plot(da,y )

error message pl plot between da vs y and dy/da vs da

Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-100.

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shiv gaur 2022-1-29

c is =1

shiv gaur 2022-1-29

how to plot dy/dda vs da

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Answer 1

Kevin Hanekom 2022-1-29

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1638635-plot-the-graph-of-function#answer_884405

在 MATLAB Online 中打开

clc;clear;close all;
l=633;
c = 1;
   
k0=2*pi/l;
ea=1.39;
da=1:300;
theta=1:70;
y=zeros(length(theta),length(da));
np=1.5;
x=(2*pi/l)*np*sind(theta);
for i=1:length(theta)
    iter = 0;
    for j=1:length(da)
        iter
ka=k0*sqrt(ea-x.^2);
f=(1-exp(2*1i.*da(j).*ka(i)))/(1+exp(2*1i.*da(j).*ka(i)));
%pfms=2*atan(1i*a.*b);
y(i,j)=2*atan(1i*c.*f);
   
%  disp(y);
    
 iter = iter + 1;
    end
end
    
 plot(da,y )  
 

What exactly is wrong?

2 个评论
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shiv gaur 2022-1-29

编辑：Walter Roberson 2022-1-31

在 MATLAB Online 中打开

this program is working pl help one pl plot da vs dy/dda

why this is not working in function define

clc;clear;close all;
l=633;
c = 1;
k0=2*pi/l;
ea=1.39;
da=1:300;
theta=1:70;
y=zeros(length(theta),length(da));
np=1.5;
x=(2*pi/l)*np*sind(theta);
function y=f(theta,da)
for i=1:length(theta)
    iter = 0;
    for j=1:length(da)
        iter
        ka=k0*sqrt(ea-x.^2);
        f=(1-exp(2*1i.*da(j).*ka(i)))/(1+exp(2*1i.*da(j).*ka(i)));
        %pfms=2*atan(1i*a.*b);
        y(i,j)=2*atan(1i*c.*f);
        
        %  disp(y);
        
        iter = iter + 1;
        plot(da,y ) 
    end
end
end  

your program in not working pl help

Walter Roberson 2022-1-31

@shiv gaur

That code never calls the function f

Reminder: your y is a 2D array that is changing in size as you go (since you do not pre-allocate). And each time you assign to a new y(i,j) location, you are plotting using the constant-sized vector da as the independent variable, and using all of the changing-size y as the dependent variable. That is going to run into size mismatches, and is also going to be attempting to plot locations in y that have not been explicitly given a value yet.

What is the point of doing the plot inside the double nested loop?

It might make sense to plot at the end of the double nested loop.

... but it would probably make more sense to return y to the calling function and let the calling function plot whatever it wants.

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