How to Build a Absolute Value Calculator

function absoluteValue(x) {
  // Handles real numbers (including edge cases)
  if (typeof x === 'number') return Math.abs(x);

  // Complex number as { re, im }
  if (x.re !== undefined && x.im !== undefined) {
    return Math.sqrt(x.re * x.re + x.im * x.im);
  }
  throw new Error('Input must be a number or complex { re, im }');
  }

  function solveAbsEquation(a, b, c) {
  // Solves |ax + b| = c -> two solutions if c > 0
  if (c < 0) return [];
  if (c === 0) return [-b / a];
  return [(-b + c) / a, (-b - c) / a];
  }

  function meanAbsoluteError(actual, predicted) {
  const n = actual.length;
  return actual.reduce((sum, val, i) => sum + Math.abs(val - predicted[i]), 0) / n;
  }