// license that can be found in the LICENSE file.

package math

// Log10 returns the decimal logarithm of x.
// The special cases are the same as for [Log].
func Log10(x float64) float64 {
	if haveArchLog10 {
		return archLog10(x)
	}
	return log10(x)
}

func log10(x float64) float64 {
	return Log(x) * (1 / Ln10)
}

// Log2 returns the binary logarithm of x.

	// approximate float64 mantissa m and decimal exponent d
	// f ~ m * 10**d
	m, _ := mant.Float64()                     // 0.5 <= |m| < 1.0
	d := float64(exp) * (math.Ln2 / math.Ln10) // log_10(2)

	// adjust m for truncated (integer) decimal exponent e
	e := int64(d)
	m *= math.Pow(10, d-float64(e))

	// ensure 1 <= |m| < 10
	switch am := math.Abs(m); {
	case am < 1-0.5e-6:

//
// Special cases are:
//
//	Log1p(+Inf) = +Inf
//	Log1p(±0) = ±0
//	Log1p(-1) = -Inf
//	Log1p(x < -1) = NaN
//	Log1p(NaN) = NaN
func Log1p(x float64) float64 {
	if haveArchLog1p {
		return archLog1p(x)
	}
	return log1p(x)
}

func log1p(x float64) float64 {
	const (
		Sqrt2M1     = 4.142135623730950488017e-01  // Sqrt(2)-1 = 0x3fda827999fcef34

org/codehaus/plexus/util/TypeFormat.class package org.codehaus.plexus.util; public final synchronized class TypeFormat { private static final char[] DIGITS; private static final int[] INT_POW_10; private static final long[] LONG_POW_10; private static final double LOG_10; private static final float FLOAT_RELATIVE_ERROR; private static final double DOUBLE_RELATIVE_ERROR; private static String[] LEADING_ZEROS; private static final double[] DOUBLE_POW_10; private void TypeFormat(); public static int indexOf(CharSequence,...

    //
    // Therefore we compute this as
    //
    //   (z + 1/2 - t(z) / log(t(z))) * log(t(z)).
    //
    // log_y = log_sqrt_two_pi + (z + one_half - t / log_t) * log_t + Log(x);
    Value t_div_log_t = rewriter.create<DivOp>(loc, t, log_t);
    Value one_half_minus_t_div_log_t =
        rewriter.create<SubOp>(loc, one_half, t_div_log_t);
    Value z_plus_one_half_minus_t_div_log_t =

   */
  @GwtIncompatible // TODO
  @SuppressWarnings("fallthrough")
  public static int log10(BigInteger x, RoundingMode mode) {
    checkPositive("x", x);
    if (fitsInLong(x)) {
      return LongMath.log10(x.longValue(), mode);
    }

    int approxLog10 = (int) (log2(x, FLOOR) * LN_2 / LN_10);
    BigInteger approxPow = BigInteger.TEN.pow(approxLog10);
    int approxCmp = approxPow.compareTo(x);

   */
  @GwtIncompatible // TODO
  @SuppressWarnings("fallthrough")
  public static int log10(BigInteger x, RoundingMode mode) {
    checkPositive("x", x);
    if (fitsInLong(x)) {
      return LongMath.log10(x.longValue(), mode);
    }

    int approxLog10 = (int) (log2(x, FLOOR) * LN_2 / LN_10);
    BigInteger approxPow = BigInteger.TEN.pow(approxLog10);
    int approxCmp = approxPow.compareTo(x);

        assertEquals(BigIntegerMath.log10(valueOf(x), mode), IntMath.log10(x, mode));
      }
    }
  }

  // Relies on the correctness of log10(int, FLOOR) and of pow(int, int).
  @GwtIncompatible // pow()
  public void testLog10Exact() {
    for (int x : POSITIVE_INTEGER_CANDIDATES) {
      int floor = IntMath.log10(x, FLOOR);
      boolean expectSuccess = IntMath.pow(10, floor) == x;

        assertEquals(BigIntegerMath.log10(valueOf(x), mode), LongMath.log10(x, mode));
      }
    }
  }

  // Relies on the correctness of log10(long, FLOOR) and of pow(long, int).
  @GwtIncompatible // TODO
  public void testLog10Exact() {
    for (long x : POSITIVE_LONG_CANDIDATES) {
      int floor = LongMath.log10(x, FLOOR);
      boolean expectedSuccess = LongMath.pow(10, floor) == x;

  // Relies on the correctness of log10(BigInteger, {HALF_UP,HALF_DOWN}).
  @GwtIncompatible // TODO
  public void testLog10HalfEven() {
    for (BigInteger x : POSITIVE_BIGINTEGER_CANDIDATES) {
      int halfEven = BigIntegerMath.log10(x, HALF_EVEN);
      // Now figure out what rounding mode we should behave like (it depends if FLOOR was
      // odd/even).
      boolean floorWasEven = (BigIntegerMath.log10(x, FLOOR) & 1) == 0;