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make it work for negative n too

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This commit is contained in:
Ahmet Inan 2019-01-18 22:21:51 +01:00
commit cf54a8e431
2 changed files with 9 additions and 1 deletions
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2
tests/unit_circle_test.cc
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@ -15,7 +15,7 @@ template <typename TYPE, typename PRECISE>
void test(int MAX)
{
for (int N = 1; N <= MAX; ++N) {
for (int n = 0; n < N; ++n) {
for (int n = -N; n <= N; ++n) {
PRECISE x = DSP::Const<PRECISE>::TwoPi() * PRECISE(n) / PRECISE(N);
PRECISE cos_err = std::abs(DSP::UnitCircle<TYPE>::cos(n, N) - std::cos(x));
assert(cos_err < std::numeric_limits<TYPE>::epsilon());

8
unit_circle.hh
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@ -56,6 +56,10 @@ public:
static constexpr TYPE cos(int n, int N)
{
return
8*n <-7*N ? cosine_approx(rad(n+N, N)) :
8*n <-5*N ? -sine_approx(rad(4*n+3*N, 4*N)) :
8*n <-3*N ? -cosine_approx(rad(2*n+N, 2*N)) :
8*n <-1*N ? sine_approx(rad(4*n+N, 4*N)) :
8*n < 1*N ? cosine_approx(rad(n, N)) :
8*n < 3*N ? -sine_approx(rad(4*n-N, 4*N)) :
8*n < 5*N ? -cosine_approx(rad(2*n-N, 2*N)) :
@ -65,6 +69,10 @@ public:
static constexpr TYPE sin(int n, int N)
{
return
8*n <-7*N ? sine_approx(rad(n+N, N)) :
8*n <-5*N ? cosine_approx(rad(4*n+3*N, 4*N)) :
8*n <-3*N ? -sine_approx(rad(2*n+N, 2*N)) :
8*n <-1*N ? -cosine_approx(rad(4*n+N, 4*N)) :
8*n < 1*N ? sine_approx(rad(n, N)) :
8*n < 3*N ? cosine_approx(rad(4*n-N, 4*N)) :
8*n < 5*N ? -sine_approx(rad(2*n-N, 2*N)) :