Vector Arccosine (Inverse Cosine) (ACOS)

ACOS applies the inverse cosine (arccos) mathematical transformation to each value in a data series, returning angles in radians. For input x where -1 ≤ x ≤ 1, ACOS returns values from 0 to π (pi). This trigonometric transform is used in advanced indicator algorithms requiring angle calculations or converting normalized oscillator values back to angular representations. ACOS is typically not applied directly to price data but to normalized indicator outputs.

Developers use ACOS in custom indicator algorithms when building cycle analysis tools, phase angle calculations, or advanced momentum oscillators. It's particularly useful for converting correlation coefficients or normalized values back into angular measurements for phase-based analysis. Combine with other trigonometric functions (SIN, COS, ATAN) for creating complex cycle indicators or quadrature systems. Essential for building custom Hilbert Transform implementations or MESA-style adaptive indicators.