Function computeFppi

src/big-decimal/utils.ts:655–666

(bits: number)

}

function computeFppi(bits: number): bigint {
  // We need ~bits·log10(2) decimal digits of PI, plus guard digits.
  const neededDigits = Math.ceil(bits * LOG10_2) + 12;
  if (neededDigits + 1 <= PI_DIGITS.length) {
    // Table path: PI ≈ piInt · 10^(-fracDigits), result = (piInt << bits)/10^frac
    const digits = PI_DIGITS.slice(0, neededDigits + 1); // +1 for the "3"
    const piInt = BigInt(digits);
    return (piInt << BigInt(bits)) / pow10(digits.length - 1);
  }
  // Beyond the table: compute on demand.
  return piChudnovskyBits(bits);
}

// ================================================================
// Fixed-point sincos (simultaneous sin and cos)