Returns a BigInteger whose value is
<code>(this<sup>exponent</sup> mod m)</code>. (Unlike {@code pow}, this
method permits negative exponents.)
@param exponent the exponent.
@param m the modulus.
@return <code>this<sup>exponent</sup> mod m</code>
@throws ArithmeticException {@code m} ≤ 0 or the exponent is
negative and this BigInteger is not <i>relatively
prime</i> to {@code m}.
@see #modInverse
Returns a BigInteger whose value is <code>(this<sup>exponent</sup> mod m)</code>. (Unlike {@code pow}, this method permits negative exponents.)
@param exponent the exponent. @param m the modulus. @return <code>this<sup>exponent</sup> mod m</code> @throws ArithmeticException {@code m} ≤ 0 or the exponent is negative and this BigInteger is not <i>relatively prime</i> to {@code m}. @see #modInverse