Highly oscillatory function

The above picture shows the highly oscillatory function

$\left({\frac {1}{6}}\left(x-{\frac {1}{4}}\right)^{3}+1\right)\sin(30x).$

It was produced by Matlab with the following script

X = linspace(-2,2,1000);
Y = ((X-1/4).^3/6 + 1) .* sin(30*X);
plot([-2 2], [0 0], ':k', X, Y, 'r');
axis([-2 2 -2 2]);
axis off;
box off;
print -dpng -r50 'hof.png';

The resulting PNG was cropped with convert -trim hof.png Highly_oscillatory_function.png