Plotting multiple piecewise functions onto the same graph

Hi!

I'm new to the program and i've been trying to plot two piecewise functions,

y(x) = piecewise(0<x<1.85, sin(523.26*pi*x), 1.85<x<3.7, 0, 3.7<x<5.55, sin(523.26*pi*x), 5.55<x<7.4, 0, 7.4<x<9.25, sin(523.26*pi*x));

and

y2(x) = piecewise(0<x<1.63, sin(463.08*pi*x), 1.63<x<3.26, 0, 3.26<x<4.89, sin(463.08*pi*x), 4.89<x<6.52, 0, 6.52<x<8.15, sin(463.08*pi*x));

onto the same graph, but i can't get the coding right. Would anyone be able to help?

Thank you so much in advance

[darova]

Maybe you have some coding so we can correct it?

[Margherita Carlon]

Oh absolutely,

I couldn't find any support for this specific case but what I tried was this (which is probably way off:

syms y1(x)

y1(x) = piecewise(0<x<1.85, sin(523.26*pi*x), 1.85<x<3.7, 0, 3.7<x<5.55, sin(523.26*pi*x), 5.55<x<7.4, 0, 7.4<x<9.25, sin(523.26*pi*x));

fplot(y1)

hold on

syms y2(x)

y2(x) = piecewise(0<x<1.63, sin(463.08*pi*x), 1.63<x<3.26, 0, 3.26<x<4.89, sin(463.08*pi*x), 4.89<x<6.52, 0, 6.52<x<8.15, sin(463.08*pi*x));

fplot(y2)

Answer 1

[Star Strider]

I coded and ran ‘y1’ as:

y1 = @(x) ((0<x) & (x<1.85)).*sin(523.26*pi*x) + ((1.85<x) & (x<3.7)).*0 + ((3.7<x) & (x<5.55)).*sin(523.26*pi*x) + ((5.55<x) & (x<7.4)).*0 + ((7.4<x) & (x<9.25)).*sin(523.26*pi*x);

t = linspace(-5, 20, 500);

figure
plot(t, y1(t))
grid

Do the same for ‘y2’. Choose as many points as you want for ‘t’.

[Margherita Carlon]

Unfortunately this wouldn't solve my problem of having both functions on the same graph. Thanks though! :)

[Star Strider]

Yes, it would!

Code ‘y2’ using the same approach I used when I coded ‘y1’, then:

figure
plot(t, y1(t),    t, y2(t))
grid

or use the hold function with two plot calls.

[Margherita Carlon]

Oh I see!! Now it works perfectly :)

do you happen to have any tips on how to change the number of points for t? Given it's really high-frequency, the mapped function dosen't look too sinusoidal anymore...

[Star Strider]

Change the third argument in the linspace function to change the number of points it creates. (The default number is 100.) See the documentation section on Vector with Specified Number of Values.