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even more correct

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calculates cube root of complex number to give more correct results.
This commit is contained in:
Viet Dinh 2015-11-03 15:17:49 -05:00
parent 537a978dcf
commit 09b0193186
2 changed files with 20 additions and 6 deletions
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22
modules/core/src/mathfuncs.cpp
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@ -2525,11 +2525,12 @@ double cv::solvePoly( InputArray _coeffs0, OutputArray _roots0, int maxIters )
num /= denom;
if( num_same_root > 1)
{
for( j = 0; j < num_same_root / 2; j++)
{
double old_num_re = num.re;
double old_num_im = num.im;
double old_num_re = num.re;
double old_num_im = num.im;
int square_root_times = num_same_root % 2 == 0 ? num_same_root / 2 : num_same_root / 2 - 1;
for( j = 0; j < square_root_times; j++)
{
num.re = old_num_re*old_num_re + old_num_im*old_num_im;
num.re = std::sqrt(num.re);
num.re += old_num_re;
@ -2541,6 +2542,19 @@ double cv::solvePoly( InputArray _coeffs0, OutputArray _roots0, int maxIters )
num.im = std::sqrt(num.im);
if( old_num_re < 0 ) num.im = -num.im;
}
if( num_same_root % 2 != 0){
Mat cube_coefs(4, 1, CV_32FC1);
Mat cube_roots(3, 1, CV_32FC2);
cube_coefs.at<float>(3) = -(std::powf(old_num_re, 3));
cube_coefs.at<float>(2) = -(15*std::powf(old_num_re, 2) + 27*std::powf(old_num_im, 2));
cube_coefs.at<float>(1) = -48*old_num_re;
cube_coefs.at<float>(0) = 64;
cv::solveCubic(cube_coefs, cube_roots);
num.re = std::cbrt(cube_roots.at<float>(0));
num.im = std::sqrtf(std::powf(num.re, 2) / 3 - old_num_re / (3*num.re));
}
}
roots[i] = p - num;

4
modules/core/test/test_math.cpp
View File

@ -2372,7 +2372,7 @@ TEST(Core_SolvePoly, regression_5599)
double prec;
prec = cv::solvePoly(coefs, r);
EXPECT_LE(prec, 1e-6);
EXPECT_EQ(4, (int)r.total());
EXPECT_EQ(4, r.total());
//std::cout << "Preciseness = " << prec << std::endl;
//std::cout << "roots:\n" << r << "\n" << std::endl;
ASSERT_EQ(CV_32FC2, r.type());
@ -2388,7 +2388,7 @@ TEST(Core_SolvePoly, regression_5599)
double prec;
prec = cv::solvePoly(coefs, r);
EXPECT_LE(prec, 1e-6);
EXPECT_EQ(2, (int)r.total());
EXPECT_EQ(2, r.total());
//std::cout << "Preciseness = " << prec << std::endl;
//std::cout << "roots:\n" << r << "\n" << std::endl;
ASSERT_EQ(CV_32FC2, r.type());