| /* | |
| * Copyright 2008-2013 NVIDIA Corporation | |
| * Copyright 2013 Filipe RNC Maia | |
| * | |
| * Licensed under the Apache License, Version 2.0 (the "License"); | |
| * you may not use this file except in compliance with the License. | |
| * You may obtain a copy of the License at | |
| * | |
| * http://www.apache.org/licenses/LICENSE-2.0 | |
| * | |
| * Unless required by applicable law or agreed to in writing, software | |
| * distributed under the License is distributed on an "AS IS" BASIS, | |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| * See the License for the specific language governing permissions and | |
| * limitations under the License. | |
| */ | |
| /*- | |
| * Copyright (c) 2007 David Schultz <das@FreeBSD.ORG> | |
| * All rights reserved. | |
| * | |
| * Redistribution and use in source and binary forms, with or without | |
| * modification, are permitted provided that the following conditions | |
| * are met: | |
| * 1. Redistributions of source code must retain the above copyright | |
| * notice, this list of conditions and the following disclaimer. | |
| * 2. Redistributions in binary form must reproduce the above copyright | |
| * notice, this list of conditions and the following disclaimer in the | |
| * documentation and/or other materials provided with the distribution. | |
| * | |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND | |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| * SUCH DAMAGE. | |
| */ | |
| /* | |
| * Adapted from FreeBSD by Filipe Maia <filipe.c.maia@gmail.com>: | |
| * freebsd/lib/msun/src/s_csqrt.c | |
| */ | |
| THRUST_NAMESPACE_BEGIN | |
| namespace detail{ | |
| namespace complex{ | |
| using thrust::complex; | |
| __host__ __device__ inline | |
| complex<double> csqrt(const complex<double>& z){ | |
| complex<double> result; | |
| double a, b; | |
| double t; | |
| int scale; | |
| /* We risk spurious overflow for components >= DBL_MAX / (1 + sqrt(2)). */ | |
| const double THRESH = 7.446288774449766337959726e+307; | |
| a = z.real(); | |
| b = z.imag(); | |
| /* Handle special cases. */ | |
| if (z == 0.0) | |
| return (complex<double>(0.0, b)); | |
| if (isinf(b)) | |
| return (complex<double>(infinity<double>(), b)); | |
| if (isnan(a)) { | |
| t = (b - b) / (b - b); /* raise invalid if b is not a NaN */ | |
| return (complex<double>(a, t)); /* return NaN + NaN i */ | |
| } | |
| if (isinf(a)) { | |
| /* | |
| * csqrt(inf + NaN i) = inf + NaN i | |
| * csqrt(inf + y i) = inf + 0 i | |
| * csqrt(-inf + NaN i) = NaN +- inf i | |
| * csqrt(-inf + y i) = 0 + inf i | |
| */ | |
| if (signbit(a)) | |
| return (complex<double>(fabs(b - b), copysign(a, b))); | |
| else | |
| return (complex<double>(a, copysign(b - b, b))); | |
| } | |
| /* | |
| * The remaining special case (b is NaN) is handled just fine by | |
| * the normal code path below. | |
| */ | |
| // DBL_MIN*2 | |
| const double low_thresh = 4.450147717014402766180465e-308; | |
| scale = 0; | |
| if (fabs(a) >= THRESH || fabs(b) >= THRESH) { | |
| /* Scale to avoid overflow. */ | |
| a *= 0.25; | |
| b *= 0.25; | |
| scale = 1; | |
| }else if (fabs(a) <= low_thresh && fabs(b) <= low_thresh) { | |
| /* Scale to avoid underflow. */ | |
| a *= 4.0; | |
| b *= 4.0; | |
| scale = 2; | |
| } | |
| /* Algorithm 312, CACM vol 10, Oct 1967. */ | |
| if (a >= 0.0) { | |
| t = sqrt((a + hypot(a, b)) * 0.5); | |
| result = complex<double>(t, b / (2 * t)); | |
| } else { | |
| t = sqrt((-a + hypot(a, b)) * 0.5); | |
| result = complex<double>(fabs(b) / (2 * t), copysign(t, b)); | |
| } | |
| /* Rescale. */ | |
| if (scale == 1) | |
| return (result * 2.0); | |
| else if (scale == 2) | |
| return (result * 0.5); | |
| else | |
| return (result); | |
| } | |
| } // namespace complex | |
| } // namespace detail | |
| template <typename ValueType> | |
| __host__ __device__ | |
| inline complex<ValueType> sqrt(const complex<ValueType>& z){ | |
| return thrust::polar(std::sqrt(thrust::abs(z)),thrust::arg(z)/ValueType(2)); | |
| } | |
| template <> | |
| __host__ __device__ | |
| inline complex<double> sqrt(const complex<double>& z){ | |
| return detail::complex::csqrt(z); | |
| } | |
| THRUST_NAMESPACE_END | |