Multi-Precision Expressions

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Overview
Comment:Change qround() to round to even on ties.
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SHA1: 8b577212453d0356f554549fd92e82c4ba377b37
User & Date: dgp 2013-05-09 14:17:12.000
Context
2013-05-09
14:51
Bump for a release of version 1.2. check-in: 5d0b7b082a user: dgp tags: trunk
14:17
Change qround() to round to even on ties. check-in: 8b57721245 user: dgp tags: trunk
12:57
Added a test to check that the mpexpr precision variable is handled on a per-interpreter basis (with the old version this was not the case) check-in: bb6410d6f3 user: arjenmarkus tags: trunk
Changes
Unified Diff Ignore Whitespace Patch
Changes to generic/qfunc.c.
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 */
NUMBER *
qround(q, places)
	NUMBER *q;		/* number to be rounded */
	long places;		/* number of decimal places to round to */
{
	NUMBER *r;
	ZVALUE tenpow, roundval, tmp1, tmp2;

	if (places < 0)
		math_error("Negative places for qround");
	if (qisint(q))
		return qlink(q);
	/*
	 * Calculate one half of the denominator, ignoring fractional results.
	 * This is the value we will add in order to cause rounding.
	 */
	zshift(q->den, -1L, &roundval);
	roundval.sign = q->num.sign;
	/*
	 * Ok, now do the actual work to produce the result.
	 */
	r = qalloc();
	ztenpow(places, &tenpow);
	zmul(q->num, tenpow, &tmp2);
	zadd(tmp2, roundval, &tmp1);
	zfree(tmp2);
	zfree(roundval);
	zquo(tmp1, q->den, &tmp2);
	zfree(tmp1);






	if (ziszero(tmp2)) {
		zfree(tmp2);
		return qlink(&_qzero_);
	}
	/*
	 * Now reduce the result to the lowest common denominator.
	 */








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 */
NUMBER *
qround(q, places)
	NUMBER *q;		/* number to be rounded */
	long places;		/* number of decimal places to round to */
{
	NUMBER *r;
	ZVALUE tenpow, roundval, tmp1, tmp2, rem;

	if (places < 0)
		math_error("Negative places for qround");
	if (qisint(q))
		return qlink(q);
	/*
	 * Calculate one half of the denominator, ignoring fractional results.
	 * This is the value we will add in order to cause rounding.
	 */
	zshift(q->den, -1L, &roundval);
	roundval.sign = q->num.sign;
	/*
	 * Ok, now do the actual work to produce the result.
	 */
	r = qalloc();
	ztenpow(places, &tenpow);
	zmul(q->num, tenpow, &tmp2);
	zadd(tmp2, roundval, &tmp1);
	zfree(tmp2);
	zfree(roundval);
	zdiv(tmp1, q->den, &tmp2, &rem);
	zfree(tmp1);
	if (ziszero(rem) && zisodd(tmp2) && ziseven(q->den)) {
		zsub(tmp2, _one_, &tmp1);
		zfree(tmp2);
		tmp2 = tmp1;
	}
	zfree(rem);
	if (ziszero(tmp2)) {
		zfree(tmp2);
		return qlink(&_qzero_);
	}
	/*
	 * Now reduce the result to the lowest common denominator.
	 */
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