Function acos_simd 

pub fn acos_simd<F>(x: &ArrayView1<'_, F>) -> Array1<F>
where
    F: Float + SimdUnifiedOps,

Compute the arccosine of each element (SIMD-accelerated).

Computes acos(x) for each element, returning values in the range [0, π].

Arguments

• x - Input 1D array with values in [-1, 1]

Returns

Array1<F> with the same length as input, where each element is the arccosine in radians. Returns NaN for |x| > 1.

Performance

• SIMD: Automatically used for large arrays (1000+ elements)
• Scalar: Used for small arrays or when SIMD is unavailable

Mathematical Properties

• Domain: [-1, 1]
• Range: [0, π]
• acos(1) = 0, acos(-1) = π
• acos(0) = π/2
• acos(-x) = π - acos(x)
• acos(cos(x)) = x for x ∈ [0, π]
• acos(x) + asin(x) = π/2
• Returns NaN for |x| > 1

Examples

use scirs2_core::ndarray::array;
use scirs2_core::ndarray_ext::elementwise::acos_simd;

let x = array![1.0_f64, 0.5, 0.0, -1.0];
let result = acos_simd(&x.view());
// Result: [0.0, π/3, π/2, π]

Applications

• 3D Graphics: Dot product angle calculations
• Machine Learning: Cosine similarity to angle conversion
• Physics: Angular momentum, rotation analysis
• Astronomy: Coordinate system transformations
• Navigation: Bearing and heading calculations

See Also

• atan_simd: Arctangent function
• asin_simd: Arcsine function
• cos_simd: Forward cosine function