public static BigFloat zero(int fracbits, int expbits, int sign) {
		return new BigFloat(fracbits, expbits, FloatKind.FINITE, sign, BigInteger.ZERO,
			2 - (1 << (expbits - 1)));
	}
Return the BigFloat with the given number of bits representing zero.

@param fracbits number of fractional bits
@param expbits number of bits in the exponent
@param sign +1 or -1
@return a BigFloat representing +zero or -zero
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/pcode/floatformat/BigFloat.java