please guide me how to make plot from –pi to pi.

in this equation

where k = 6+ 6, and the size = 30+ 9.

The plot should be from –pi to pi

X = size*cos(kt)*cos(t).

Y = size*cos(kt)*sin(t).

i use to make it like this but it gives me errors it still asks me about t is undefined

k = 6 + 6;

size = 30 + 9;

X = size * cos (k*t) * cos(t);

Y = size * cos (k*t) * sin(t);

Answer 1

[Torsten]

k = 6 + 6;                  
size =  30 + 9;
t = linspace(-pi,pi,1000);
X = size * cos (k*t) .* cos(t);
Y = size * cos (k*t) .* sin(t);
plot(X,Y)

[Image Analyst]

Except that they should not use size as the name of a variable.

[Saleh]

thank you very much also i have other questions to ask i want to make a table

[Torsten]

https://de.mathworks.com/help/matlab/matlab_prog/create-a-table.html

[Saleh]

i should make table and graph as i want semester marks as per the table suing either stem or bar function. The graph should be entitled “Spring Semester Marks”, with x and y axis labelled. Customize your graphs to be as unique as possible

title ('Spring Semester Marks')

xlable('Spring Semester Marks')

ylable('Spring Semester Marks')

patients = table(booksname,1,2,3,4)

is it like this ?

Answer 2

[David Hill]

k = 12;                  
size =  39;
X =@(t) size * cos (k*t) .* cos(t);
Y =@(t) size * cos (k*t) .* sin(t);
t=-pi:.01:pi;
plot(t,X(t),t,Y(t))

[Image Analyst]

Except that they should not use size as the name of a variable.

Answer 3

[Image Analyst]

Try this:

t = linspace(-pi, pi, 1000);
period = pi/2;                  
amplitude =  39;
k = 12;
X = amplitude * cos (2 * pi * t * k / period) .* cos(2 * pi * t / period);
subplot(3, 1, 1);
plot(t, X, 'b-', 'LineWidth', 2);
grid on;
title('X')
Y = amplitude * cos (2 * pi * t * k / period) .* sin(2 * pi * t / period);
subplot(3, 1, 2);
plot(t, Y, 'r-', 'LineWidth', 2);
grid on;
title('Y')
subplot(3, 1, 3);
plot(X, Y, 'm-')
axis equal
title('Y vs. X')

[Saleh]

thank you very much i appreciate it