void Curve::_get_vector (double x0, double x1, float *vec, int32_t veclen) { double rx, lx, hx, max_x, min_x; int32_t i; int32_t original_veclen; int32_t npoints; if (veclen == 0) { return; } if ((npoints = _list.events().size()) == 0) { /* no events in list, so just fill the entire array with the default value */ for (int32_t i = 0; i < veclen; ++i) { vec[i] = _list.default_value(); } return; } if (npoints == 1) { for (int32_t i = 0; i < veclen; ++i) { vec[i] = _list.events().front()->value; } return; } /* events is now known not to be empty */ max_x = _list.events().back()->when; min_x = _list.events().front()->when; if (x0 > max_x) { /* totally past the end - just fill the entire array with the final value */ for (int32_t i = 0; i < veclen; ++i) { vec[i] = _list.events().back()->value; } return; } if (x1 < min_x) { /* totally before the first event - fill the entire array with * the initial value. */ for (int32_t i = 0; i < veclen; ++i) { vec[i] = _list.events().front()->value; } return; } original_veclen = veclen; if (x0 < min_x) { /* fill some beginning section of the array with the initial (used to be default) value */ double frac = (min_x - x0) / (x1 - x0); int64_t fill_len = (int64_t) floor (veclen * frac); fill_len = min (fill_len, (int64_t)veclen); for (i = 0; i < fill_len; ++i) { vec[i] = _list.events().front()->value; } veclen -= fill_len; vec += fill_len; } if (veclen && x1 > max_x) { /* fill some end section of the array with the default or final value */ double frac = (x1 - max_x) / (x1 - x0); int64_t fill_len = (int64_t) floor (original_veclen * frac); float val; fill_len = min (fill_len, (int64_t)veclen); val = _list.events().back()->value; for (i = veclen - fill_len; i < veclen; ++i) { vec[i] = val; } veclen -= fill_len; } lx = max (min_x, x0); hx = min (max_x, x1); if (npoints == 2) { /* linear interpolation between 2 points */ /* XXX: this numerator / denominator stuff is pretty grim, but it's the only way I could get the maths to be accurate; doing everything with pure doubles gives ~1e-17 errors in the vec[i] computation. */ /* gradient of the line */ double const m_num = _list.events().back()->value - _list.events().front()->value; double const m_den = _list.events().back()->when - _list.events().front()->when; /* y intercept of the line */ double const c = double (_list.events().back()->value) - (m_num * _list.events().back()->when / m_den); /* dx that we are using */ double dx_num = 0; double dx_den = 1; if (veclen > 1) { dx_num = hx - lx; dx_den = veclen - 1; for (int i = 0; i < veclen; ++i) { vec[i] = (lx * (m_num / m_den) + m_num * i * dx_num / (m_den * dx_den)) + c; } } else { vec[0] = lx * (m_num / m_den) + c; } return; } if (_dirty) { solve (); } rx = lx; double dx = 0; if (veclen > 1) { dx = (hx - lx) / (veclen - 1); } for (i = 0; i < veclen; ++i, rx += dx) { vec[i] = multipoint_eval (rx); } }
void Curve::_get_vector (double x0, double x1, float *vec, int32_t veclen) { double rx, dx, lx, hx, max_x, min_x; int32_t i; int32_t original_veclen; int32_t npoints; if ((npoints = _list.events().size()) == 0) { for (i = 0; i < veclen; ++i) { vec[i] = _list.default_value(); } return; } /* events is now known not to be empty */ max_x = _list.events().back()->when; min_x = _list.events().front()->when; lx = max (min_x, x0); if (x1 < 0) { x1 = _list.events().back()->when; } hx = min (max_x, x1); original_veclen = veclen; if (x0 < min_x) { /* fill some beginning section of the array with the initial (used to be default) value */ double frac = (min_x - x0) / (x1 - x0); int32_t subveclen = (int32_t) floor (veclen * frac); subveclen = min (subveclen, veclen); for (i = 0; i < subveclen; ++i) { vec[i] = _list.events().front()->value; } veclen -= subveclen; vec += subveclen; } if (veclen && x1 > max_x) { /* fill some end section of the array with the default or final value */ double frac = (x1 - max_x) / (x1 - x0); int32_t subveclen = (int32_t) floor (original_veclen * frac); float val; subveclen = min (subveclen, veclen); val = _list.events().back()->value; i = veclen - subveclen; for (i = veclen - subveclen; i < veclen; ++i) { vec[i] = val; } veclen -= subveclen; } if (veclen == 0) { return; } if (npoints == 1) { for (i = 0; i < veclen; ++i) { vec[i] = _list.events().front()->value; } return; } if (npoints == 2) { /* linear interpolation between 2 points */ /* XXX I'm not sure that this is the right thing to do here. but its not a common case for the envisaged uses. */ if (veclen > 1) { dx = (hx - lx) / (veclen - 1) ; } else { dx = 0; // not used } double slope = (_list.events().back()->value - _list.events().front()->value)/ (_list.events().back()->when - _list.events().front()->when); double yfrac = dx*slope; vec[0] = _list.events().front()->value + slope * (lx - _list.events().front()->when); for (i = 1; i < veclen; ++i) { vec[i] = vec[i-1] + yfrac; } return; } if (_dirty) { solve (); } rx = lx; if (veclen > 1) { dx = (hx - lx) / (veclen - 1); } else { dx = 0; } for (i = 0; i < veclen; ++i, rx += dx) { vec[i] = multipoint_eval (rx); } }