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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 Log
// interval Log(const interval& x);
// void testLog();
static const interval domain{0, HUGE_VAL, 0};
interval interval_algebra::Log(const interval& x)
{
interval i = intersection(x, domain);
if (i.isEmpty()) {
return empty();
}
// lowest slope is at the highest bound of the interval
int precision = exactPrecisionUnary(
log, i.hi(),
-pow(2, i.lsb())); // -pow because we take the FP number right before the higher bound
if ((precision == INT_MIN) || taylor_lsb) {
/* double delta = -log(1 - pow(2, i.lsb()) / i.hi());
precision = floor((double)log2(delta));*/
precision = floor(i.lsb() - (double)log2(abs(i.hi())));
}
return {log(i.lo()), log(i.hi()), precision};
}
void interval_algebra::testLog()
{
/* analyzeUnaryMethod(10, 10000, "log", interval(0, 10, -6), log, &interval_algebra::Log);
analyzeUnaryMethod(10, 10000, "log", interval(0, 10, -12), log, &interval_algebra::Log);
analyzeUnaryMethod(10, 10000, "log", interval(0, 10, -20), log, &interval_algebra::Log);
analyzeUnaryMethod(10, 10000, "log", interval(0, 10, -24), log, &interval_algebra::Log);*/
analyzeUnaryMethod(10, 10000, "log", interval(-10, 10, -24), log, &interval_algebra::Log);
// check("test algebra Log", Log(interval(1, 10)), interval(log(1), log(10)));
// check("test algebra Log", Log(interval(0, 10)), interval(log(0), log(10)));
// check("test algebra Log", Log(interval(-10, 10)), interval(log(0), log(10)));
}
} // namespace itv
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