I am plotting in 2D on gnuplot through Ubuntu. When defining my equation for 'radius of curvature' a function of theta=x of variables sin and cos functions, respectively, I get an error message saying 'undefined variable: sin' or cos. I am simply defining the variable R=1 in the equation then setting
f(x) = R*sin(x)*(1+4*cos**2*(x)**(1.5)) / 2*(2*sin**2*(x)+3*cos**2*(x))
then saying plot f(x). What am I doing wrong?
With your function
f(x) = R*sin(x)*(1+4*cos**2*(x)**(1.5)) / 2*(2*sin**2*(x)+3*cos**2*(x))
you should actually get an error undefined variable: cos,
Your intention probably was:
f(x) = R*sin(x)*(1+4*cos(x)**2**(1.5)) / 2*(2*sin(x)**2 + 3*cos(x)**2)
or maybe
f(x) = R*sin(x)*(1+4*cos(x)**2**(1.5)) / (2*(2*sin(x)**2 + 3*cos(x)**2))
where I'm not sure whether in the first part this should really be:
cos(x)**2**1.5
or maybe: R*sin(x)*(1+4*cos(x)**2)**1.5
Mind the parentheses.
cos**2(x)as meaningcos(x)**2. It thinks you are squaring a variable named cos.