Plotting a function over an interval- Unexpected output

I need to plot this function and this is my code:

C=1.000e-7; %10^-7

x= [0:h:xf];

y=(2*pi*(2*pi*(exp(-10000*x))+(sin(20000*pi*x)))+cos(20000*pi*x))/ ( 2000000*(1+4*pi^2));

plot(x,y/C);

I expect to get a sinusoidal output scaled by 1/C. Instead I get what you can see in the picture. Can anyone tell me what am I doing wrong?

I am new to MATLAB so apologies for asking such a question.

Answer 1

[David Hill]

C=1.000e-7; %10^-7
x= [0:.00001:.04];%need to plot smaller interval
y=(2*pi*(2*pi*(exp(-10000*x))+(sin(20000*pi*x)))+cos(20000*pi*x))/ ( 2000000*(1+4*pi^2));
plot(x,y/C);

[Kleanthis-Marios Papadopoulos]

Thank you. This seems to work correctly. The solution is part of numerical analysis coursework.