hi there i have this code it doesnot work will and I need help with finding the error

the code is

step=2.5; t11=0; t12=180; t21=0; t22=90;

a1=1; a2=0.5;

hold on

for i=t11:step:t12;

for k=t21:step:t22;

x=a1*cos(i*pi/180)+a2*cos((pi/180)*(i+k));

y=a1*sin(i*pi/180)+a2*sin((pi/180)*(i+k));

plot(x,y)

end

end

but it doesnot plot any thing

Answer 1

[Caleb Wilkins]

Hello,

I would solve your problem by saving the data into a matrix that can be plotted later (after the loop). I have modified your code to produce this.

Here is the modified code with comments. Hope this helps.

step=2.5; t11=0; t12=360; t21=0; t22=360;
a1=1; a2=0.5;

x = zeros(length(t11:step:t12),length(t21:step:t22)); %pre allocate the size. This helps if you want to easily change values also. It will not have remenant data left from previous "runs"
y = zeros(length(t11:step:t12),length(t21:step:t22));

index=1; %initilaize the index variable. Must be greater than 0.
for i=t11:step:t12
    for k=t21:step:t22
        x(index)=a1*cos(i*pi/180)+a2*cos((pi/180)*(i+k));
        y(index)=a1*sin(i*pi/180)+a2*sin((pi/180)*(i+k));
        index = index+1; %add one to the index before next cycle.
    end
end

plot(x,y,'k') %plot the arrays of data with a black line.

[Kareem Alnahar]

Thank you so much that's so helpful

[Steven Lord]

Another potential approach, if you need the plot to appear and be updated at each iteration, would be to use an animatedline to which you addpoints inside the loop. Use the example on the animatedline documentation page as a model.