How to create a semicircular pulse function?

I need to write a function that adds a rectangularPulse, a triangularPulse and a semicircular pulse, but i can't find a way to do this. All the answers I find here plots directly the semicircle, but it doesn't create a function that i can add to others and it isn't a pulse.

Basically, what I'm trying to do is:

syms x
p = 4*rectangularPulse(-4,4,x);
a = (-pi)*triangularPulse(0,2,x);
c = (-1)*semicircularPulse(-4,0,x); %% where -4 is the rising edge of the pulse, 0 is the falling edge and the radius is 2. (|-4+0|/2)
fun = p + a + c;
fplot(fun, [-5 5])

But I still couldn't figure how I'm going to do this semicircularPulse function.

Thank you.

Answer 1

[Image Analyst]

Have you seen the FAQ: How to create an arc? I bet you can figure it out from there.

[Matheus Angelo]

I saw this article before, but still don't know how to create a pulse from that. Thanks anyway

[Image Analyst]

Really? OK so I took the FAQ and put in your numbers and it seemed to work fine:

% Define parameters of the arc.
xCenter = -2;
yCenter = 0; 
radius = 2;
% Define the angle theta as going from 0 to 180 degrees in 100 steps.
theta = linspace(0, 180, 100);
% Define x and y using "Degrees" version of sin and cos.
x = radius * cosd(theta) + xCenter; 
c = radius * sind(theta) + yCenter; 
% Now plot the points.
plot(x, c, 'b-', 'LineWidth', 2); 
axis equal; 
grid on;
xlabel('x', 'FontSize', 20);
ylabel('c', 'FontSize', 20);

Let me see your code so I can tell what you did wrong.

[Matheus Angelo]

I did exactly that, but I need to transform the semicircular in a pulse, like the rectangular pulse and the triangular pulse. Basically, I need a function that gives me 0 outside the semicircle, just like this but with a semicircle.

[Image Analyst]

I don't have the Symbolic toolbox so all I can do is to do it numerically.

Basically just make a function that ignores the signal and makes an array that is all zero except it's 1 at x=0. Or make two ramps if there are lots of x values.

But your first question didn't seem to say that you wanted to transform the circle into a triangle. It seemed to say you need to create three differently shaped signals and simply add them together. So which is it?

1. Create three signals and add together, or
2. Make a transform that makes any signal into that triangle?