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/* Copyright 2023 Yann ORLAREY
*
* 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.
*/
#include <algorithm>
#include <functional>
#include <random>
#include "check.hh"
#include "interval_algebra.hh"
#include "interval_def.hh"
namespace itv {
//------------------------------------------------------------------------------------------
// Interval Atanh
// Calculates the inverse hyperbolic tangent of x; that is the value whose hyperbolic tangent is x.
// interval Atanh(const interval& x);
// void testAtanh();
static const interval domain(std::nexttoward(-1, 0), std::nexttoward(1, 0),
0); // interval ]-1,1[, precision 0
interval interval_algebra::Atanh(const interval& x)
{
interval i = intersection(domain, x);
if (i.isEmpty()) {
return empty();
}
double v = minValAbs(x);
double sign = signMinValAbs(x);
int precision = exactPrecisionUnary(std::atanh, v, sign * std::pow(2, x.lsb()));
if ((precision == INT_MIN) || taylor_lsb) {
precision = std::floor(x.lsb() - (double)std::log2(1 - v * v));
}
return {atanh(i.lo()), atanh(i.hi()), precision};
}
void interval_algebra::testAtanh()
{
analyzeUnaryMethod(10, 1000, "atanh", interval(-1 + std::pow(2, -3), 1 - std::pow(2, -3), -3),
atanh, &interval_algebra::Atanh);
analyzeUnaryMethod(10, 1000, "atanh", interval(-1 + std::pow(2, -5), 1 - std::pow(2, -5), -5),
atanh, &interval_algebra::Atanh);
analyzeUnaryMethod(10, 1000, "atanh",
interval(-1 + std::pow(2, -10), 1 - std::pow(2, -10), -10), atanh,
&interval_algebra::Atanh);
analyzeUnaryMethod(10, 1000, "atanh",
interval(-1 + std::pow(2, -15), 1 - std::pow(2, -15), -15), atanh,
&interval_algebra::Atanh);
analyzeUnaryMethod(10, 1000, "atanh",
interval(-1 + std::pow(2, -20), 1 - std::pow(2, -20), -20), atanh,
&interval_algebra::Atanh);
}
} // namespace itv
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