how to plot sine wave without built in function ?

Hi.. um i wanted to ask a small question .. um a beginner in Matlab so .. i wanted to know if there's a way to create a sine wave without the sine function .. ? waiting for your reply

[Adam]

Obviously you could estimate one, but why would you want to?

[Guillaume]

Probably not the answer you want, but conforms exactly to your request:

sine = @(x) cos(pi/2 - x);

[Shaheer Ali]

thankyou but i want o plot it without the builtin sine cosine functions

Answer 1

[Star Strider]

I don’t know why you would want to, but this works with reasonably accuracy:

sine = @(x) sum((x.^[1:2:18]) .* -((-1).^[1:9]) ./ factorial([1:2:18]));

[Shaheer Ali]

umm im still a beginner so can you please wxplain it a little and specify how to plot using this .. please .. thankyou !

[Star Strider]

My pleasure!

To plot it, first define a range for the angle, then use the function on that range. I wrote it quickly, so it doesn’t take vector arguments and the loop is necessary:

sine = @(x) sum((x.^[1:2:18]) .* -((-1).^[1:9]) ./ factorial([1:2:18]));
angl = linspace(-2*pi, 2*pi, 500);
for k1 = 1:length(angl)
    sineval(k1) = sine(angl(k1));
end

figure(1)
plot(angl, sineval)
grid

Answer 2

[Thomas Alex]

similarly how to plot 2 different sine waves with a phse difference?