how do i use imwrite
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I have this code that plots a 3D Lorenz attractor. However when i try to write the plot to file using imwrite, it brings up an error:
Error in lorenzzz (line 31)
imwrite(Lorenzattractor,'Lattractor','.png');
>>
a=10; %sigma
b=8/3; %beta
r=28; %rho
h=0.004; %time step size dt
x=0;y=1; z=0;
f=zeros(1,3); %creates an array to hold the values of x,y,z
f=[x y z];
k=1; %the first row of the array
for t=0:h:100
k1_x=a*(y(k)-x(k));
k2_x=a*(y(k)-x(k))+(k1_x*h*0.5);
k3_x=a*(y(k)-x(k))+(k2_x*h*0.5);
k4_x=a*(y(k)-x(k))+(k3_x*h);
x(k+1)=x(k)+(k1_x+2*k2_x+2*k3_x+k4_x)*h/6; %value of x at t+1
k1_y=x(k)*(r-z(k))-y(k);
k2_y=(x(k)*(r-z(k))-y(k))+k1_y*h*0.5;
k3_y=(x(k)*(r-z(k))-y(k))+k2_y*h*0.5;
k4_y=(x(k)*(r-z(k))-y(k))+k3_y*h*0.5;
y(k+1)=y(k)+(k1_y+(2*k2_y)+(2*k3_y)+(k4_y))*h/6; %value of y at t+1
k1_z=x(k)*y(k)-b*z(k);
k2_z=(x(k)*y(k)-b*z(k))+k1_z*h*0.5;
k3_z=(x(k)*y(k)-b*z(k))+k2_z*h*0.5;
k4_z=(x(k)*y(k)-b*z(k))+k3_z*h*0.5;
z(k+1)=z(k)+(k1_z+(2*k2_z)+(2*k3_z)+(k4_z))*h/6; %value of z at t+1
k=k+1;
end
plot3(x,y,z); grid on;
xlabel('x'); ylabel('y');
zlabel('z');
title('Lorenzattractor');
%the code runs up to this point.
imwrite(Lorenzattractor,'Lattractor','.png');
brings error: Error in lorenzzz (line 31)
imwrite(Lorenzattractor,'Lattractor','.png');
>>
2 个评论
Image Analyst
2012-10-6
Edit your post. Highlight your code. Click the {}Code icon to format like normal code.
Ejike
2012-10-6
采纳的回答
Image Analyst
2012-10-6
编辑：Image Analyst
2012-10-6
Ejike I answered this earlier this morning. However somehow your question got deleted. Thanks to Lazarus, I still have my deleted answer. Here it is:
*Ejike: You do not have a variable in your program called Lorenzattractor. Anyway, you should be using export_fig. See the FAQ http://matlab.wikia.com/wiki/FAQ#How_do_I_save_my_figure.2C_axes.2C_or_image.3F_I.27m_having_trouble_with_the_built_in_MATLAB_functions.*
export_fig('Lattractor.png');
Also, please learn how to format your code. It's not hard, just make sure you have a blank line before it, then highlight all your code and click the {}Code icon above the edit box.
2 个评论
Ejike
2012-10-6
Image Analyst
2012-10-7
Actually it was in your duplicate question in the newsgroup: http://www.mathworks.com/matlabcentral/newsreader/view_thread/323589
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