And now we shall learn to draw a function, with numpy and matplotlib.pyplot as well.

First we must have numpy and matplotlib.pyplot available, so we type from numpy import * and from matplotlib.pyplot import *.

We must define a function The first method is with a for loop.

It is the more general method.

We must define vectors x and y.

We shall define two vectors y1 equal to cos x and y2 equal to sin x.

We must initialize the vectors.

with zeros and a certain length.

We choose 101.

Then we make a for loop for k going from -50 to 50.

51 is not included.

Then we define x of k plus 50, that is k multiplied by pi over 10.

It is a sampling from minus 5 pi to 5 pi.

Then we define y1 of k plus 50, that is the cos of x of k plus 50.

And y2 of k plus 50, that is the sin of x of k plus 50.

So we define element by element the cosine of x and the sinus of x.

And then we shall plot the functions y1 equal to cos of x and y2 equal to sin of x.

Launch Anaconda in Spyder and follow me to see how to do that.

First we define a new file.

Then we give it a name.

We place it in the right directory and we call it Functions Plotting dot py.

We first type from numpy import * and from matplotlib.pyplot import star.

Then we define, we initialize, x with zeros in a vector of length 101.

We copy equals zeros of 101.

Because we want to initialize y1 with the same vector filled with zeros and the same length.

And y2 the same way.