3. Write an Octave script to generate x-values ranging from - to with 100 points. Define four different y-values using the following equations:

y1 = cos(x) y2 = exp(-0.2*x) * sin(2*x) y3 = x^2 / (2*pi^2) y4 = 0.5 * tanh(x)

Plot these four curves on the same graph with varying line styles and colors. Include appropriate labels for the x-axis and y-axis, a title for the plot, and a legend.