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/* Vector_extensions.cpp
*
* Copyright (C) 2022 David Weenink
*
* This code is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This code is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this work. If not, see <http://www.gnu.org/licenses/>.
*/
#include "Sampled.h"
#include "Vector_extensions.h"
#include "enums_getText.h"
#include "Vector_extensions_enums.h"
#include "enums_getValue.h"
#include "Vector_extensions_enums.h"
double Vector_getNearestLevelCrossing (Vector me, integer channel, double position, double level, kVectorSearchDirection searchDirection) {
if (position < my xmin || position > my xmax)
return undefined;
VEC amplitude = my channel (channel);
if (my nx == 1)
return ( amplitude [1] == level ? my x1 : undefined );
integer leftSample = Sampled_xToLowIndex (me, position);
Melder_clip (1_integer, & leftSample, my nx - 1);
const integer rightSample = leftSample + 1;
auto interpolateLinear = [&] (integer i1) -> double {
const double x1 = Sampled_indexToX (me, i1); // x2 = x1 + dx
const double y1 = amplitude [i1], y2 = amplitude [i1 + 1];
/*
y = x1 + (x2 - x1) * (y1 - level) / (y1 - y2) = x1 + dx * (y1 - level) / (y1 - y2)
*/
return x1 + my dx * (y1 - level) / (y1 - y2); // y1 <> y2!
};
/*
Are we already at a level crossing?
*/
if (leftSample >= 1 && rightSample <= my nx &&
(amplitude [leftSample] >= level) != (amplitude [rightSample] >= level))
{
const double crossing = interpolateLinear (leftSample);
return searchDirection == kVectorSearchDirection::LEFT ?
( crossing <= position ? crossing : undefined ) :
( crossing >= position ? crossing : undefined );
}
double leftCrossing = undefined;
if (searchDirection == kVectorSearchDirection::LEFT || searchDirection == kVectorSearchDirection::NEAREST) {
for (integer ileft = leftSample - 1; ileft >= 1; ileft --)
if ((amplitude [ileft] >= level) != (amplitude [ileft + 1] >= level)) {
leftCrossing = interpolateLinear (ileft);
break;
}
if (searchDirection == kVectorSearchDirection::LEFT)
return leftCrossing;
}
double rightCrossing = undefined;
if (searchDirection == kVectorSearchDirection::RIGHT || searchDirection == kVectorSearchDirection::NEAREST) {
for (integer iright = rightSample + 1; iright <= my nx; iright ++)
if ((amplitude [iright] >= level) != (amplitude [iright - 1] >= level)) {
rightCrossing = interpolateLinear (iright - 1);
break;
}
if (searchDirection == kVectorSearchDirection::RIGHT)
return rightCrossing;
}
return
isdefined (leftCrossing) && isdefined (rightCrossing) ?
( position - leftCrossing < rightCrossing - position ? leftCrossing : rightCrossing )
: isdefined (leftCrossing) ? leftCrossing
: isdefined (rightCrossing) ? rightCrossing
: undefined;
}
/* End of file Vector_extensions.cpp */
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