I have a code but it keep saying "invalid expression. when calling a function or indexing a variable, use parentheses. otherwise check for mismatched delimiters.

x1=linspace(0,8.*pi,50)
y1=exp(-0.1.*x1).*cos(5.*x1)

xx1=(0,8.*pi,1000)
x2=linspace(-1,1)
yy1=exp(-0.1.*x2).*cos(5.*x2)
y2=sinh(5.*x3)
x3=(-4,4)
y3=0.5+2.*cos(0.5.*pi.*x3)/pi-2.*cos(1.5.*pi.*x3)/(3.*pi)+2.*cos(2.5.*pi.*x3)/(5.*pi)
x4=linspace(-4,4)
y4=y3-2.*cos(3.5.*pi.*x4)/(7.*pi)+2.*cos(4.5.*pi.*x4)/(9.*pi)

plot(x1,y1)
plot(xx1,yy1)
plot(x2,y2)
plot(x3,y3)
plot(x4,y4)

Answer 1

[Rik]

The reason is these two lines:

xx1=(0,8.*pi,1000)
x3=(-4,4)

Did you maybe forget linspace?

Anyway, this isn't valid Matlab syntax. If you thought it was, I encourage you to do a basic Matlab tutorial.