Two discrete box-pulse signals f and g are convolved: the result at each point is the sum of f[m] · g[n − m] over all m.

Controls:

• A width / B width: change the box-pulse widths of f and g.

• B shift: slide g left or right relative to f before convolving.

The math:

(f ★ g)[n] = Σₘ f[m] · g[n − m]

Convolving two boxes of a and b samples gives a trapezoid of a + b − 1 samples.