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Fix cost evaluation. (chain product for integral power)

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Chen-Pang He
2012-09-22 17:37:14 +08:00
parent 446d14f6ad
commit dd8034bd1c
2 changed files with 35 additions and 18 deletions
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30
unsupported/Eigen/src/MatrixFunctions/MatrixPower.h
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@@ -157,7 +157,7 @@ typename MatrixType::RealScalar MatrixPower<MatrixType>::modfAndInit(RealScalar
*intpart = std::floor(x);
RealScalar res = x - *intpart;
if (!m_init && res) { // !init && res
if (!m_init && res) {
const ComplexSchur<MatrixType> schurOfA(m_A);
m_T = schurOfA.matrixT();
m_U = schurOfA.matrixU();
@@ -209,29 +209,41 @@ template<typename MatrixType>
template<typename PlainObject, typename ResultType>
void MatrixPower<MatrixType>::computeIntPower(const PlainObject& b, ResultType& res, RealScalar p)
{
if (b.cols() > m_A.cols()) {
if (b.cols() >= m_A.cols()) {
m_tmp2 = MatrixType::Identity(m_A.rows(),m_A.cols());
computeIntPower(m_tmp2, p);
res.noalias() = m_tmp2 * b;
} else {
}
else {
RealScalar pp = std::abs(p);
int cost = internal::binary_powering_cost(pp);
int squarings, applyings = internal::binary_powering_cost(pp, &squarings);
bool init = false;
if (p==0) {
res = b;
return;
}
if (p<0) m_tmp1 = m_A.inverse();
else m_tmp1 = m_A;
else if (p>0) {
m_tmp1 = m_A;
}
else if (b.cols() * (pp - applyings) <= m_A.cols() * squarings) {
PartialPivLU<MatrixType> A(m_A);
res = A.solve(b);
for (--pp; pp >= 1; --pp)
res = A.solve(res);
return;
}
else {
m_tmp1 = m_A.inverse();
}
while (b.cols()*pp > m_A.cols()*cost) {
while (b.cols() * (pp - applyings) > m_A.cols() * squarings) {
if (std::fmod(pp, 2) >= 1) {
apply(b, res, init);
--cost;
--applyings;
}
m_tmp1 *= m_tmp1;
--cost;
--squarings;
pp /= 2;
}
for (; pp >= 1; --pp)