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/*
* Copyright 2012, The Android Open Source Project
*
* 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 "TimeSeries.h"
#include <math.h>
#include <string.h>
namespace android {
TimeSeries::TimeSeries()
: mCount(0),
mSum(0.0) {
}
void TimeSeries::add(double val) {
if (mCount < kHistorySize) {
mValues[mCount++] = val;
mSum += val;
} else {
mSum -= mValues[0];
memmove(&mValues[0], &mValues[1], (kHistorySize - 1) * sizeof(double));
mValues[kHistorySize - 1] = val;
mSum += val;
}
}
double TimeSeries::mean() const {
if (mCount < 1) {
return 0.0;
}
return mSum / mCount;
}
double TimeSeries::sdev() const {
if (mCount < 1) {
return 0.0;
}
double m = mean();
double sum = 0.0;
for (size_t i = 0; i < mCount; ++i) {
double tmp = mValues[i] - m;
tmp *= tmp;
sum += tmp;
}
return sqrt(sum / mCount);
}
} // namespace android
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