acos function

dynamic acos(dynamic x)

Returns the arccosine of a number in radians.

Example:

print(acos(1));  // Output: 0.0

Example 2:

print(acos(Complex(1, 2))); // Output: 1.1437177404024204 - 1.528570919480998i

Implementation

dynamic acos(dynamic x) {
  if (x is num) {
    if (x >= -1 && x <= 1) {
      return math.acos(x);
    } else {
      // Since math.acos does not support inputs outside [-1, 1], we need to use the complex formula
      Complex z = Complex(x, 0);
      dynamic result =
          -Complex(0, 1) * log(z + Complex(0, 1) * sqrt(Complex(1, 0) - z * z));
      return result;
    }
  } else if (x is Complex) {
    // Using the formula: acos(z) = -i * log(z + i * sqrt(1 - z^2))
    return -Complex(0, 1) *
        log(x + Complex(0, 1) * sqrt(Complex(1, 0) - x * x));
  } else {
    throw ArgumentError('Input should be either num or Complex');
  }
}