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fix model generation, add rewrite rules for sin(acos(x)) reduction to help model validation. Issue #680

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-07-13 11:12:27 -07:00
parent 247e94a7c0
commit 3a70b6aab4
3 changed files with 28 additions and 9 deletions
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19
src/ast/rewriter/arith_rewriter.cpp
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@ -1196,11 +1196,17 @@ expr * arith_rewriter::mk_sin_value(rational const & k) {
}
br_status arith_rewriter::mk_sin_core(expr * arg, expr_ref & result) {
if (is_app_of(arg, get_fid(), OP_ASIN)) {
expr * m, *x;
if (m_util.is_asin(arg, x)) {
// sin(asin(x)) == x
result = to_app(arg)->get_arg(0);
result = x;
return BR_DONE;
}
if (m_util.is_acos(arg, x)) {
// sin(acos(x)) == sqrt(1 - x^2)
result = m_util.mk_power(m_util.mk_sub(m_util.mk_real(1), m_util.mk_mul(x,x)), m_util.mk_numeral(rational(1,2), false));
return BR_REWRITE_FULL;
}
rational k;
if (is_numeral(arg, k) && k.is_zero()) {
// sin(0) == 0
@ -1214,7 +1220,6 @@ br_status arith_rewriter::mk_sin_core(expr * arg, expr_ref & result) {
return BR_REWRITE_FULL;
}
expr * m;
if (is_pi_offset(arg, k, m)) {
rational k_prime = mod(floor(k), rational(2)) + k - floor(k);
SASSERT(k_prime >= rational(0) && k_prime < rational(2));
@ -1250,11 +1255,15 @@ br_status arith_rewriter::mk_sin_core(expr * arg, expr_ref & result) {
}
br_status arith_rewriter::mk_cos_core(expr * arg, expr_ref & result) {
if (is_app_of(arg, get_fid(), OP_ACOS)) {
expr* x;
if (m_util.is_acos(arg, x)) {
// cos(acos(x)) == x
result = to_app(arg)->get_arg(0);
result = x;
return BR_DONE;
}
if (m_util.is_asin(arg, x)) {
// cos(asin(x)) == ...
}
rational k;
if (is_numeral(arg, k) && k.is_zero()) {