Pseudo sinusoidal waveform II

Mr Stenzel, CEO of Waldorf Music GmbH, decided to disclose his excellent pseudo sinusoidal formula: $4x \cdot (1-|x|)$.

Here is a plot of the function:

As you can see, this really looks like a sine wave! The following error plot reveals a maximum error of 0.056:

In terms of distortion, Mr. Stenzel is right. This function is 2.85 times better than the previous pseudo sine.