| /* |
| * Copyright (C) 2011 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. |
| */ |
| |
| #ifndef ANDROID_FILTERFW_CORE_STATISTICS_H |
| #define ANDROID_FILTERFW_CORE_STATISTICS_H |
| |
| namespace android { |
| namespace filterfw { |
| |
| // An incrementally-constructed Normal distribution. |
| class IncrementalGaussian { |
| public: |
| IncrementalGaussian(); |
| |
| void Add(float value); |
| |
| float NumSamples() const { return n_; } |
| float Mean() const { return mean_; } |
| float Var() const { return var_; } |
| float Std() const; |
| float Pdf(float value) const; |
| |
| private: |
| int n_; |
| float sum_x_; |
| float sum_x2_; |
| float mean_; |
| float var_; |
| float exp_denom_; |
| float pdf_denom_; |
| }; |
| |
| // Discrete-time implementation of a simple RC low-pass filter: |
| // exponentially-weighted moving average. |
| class RCFilter { |
| public: |
| explicit RCFilter(float gain) |
| : gain_(gain), n_(0), value_(0.0f) {} |
| |
| void Add(float measurement) { |
| value_ = n_++ ? gain_ * measurement + (1.0f - gain_) * value_ : measurement; |
| } |
| |
| void Reset() { n_ = 0; } |
| |
| int NumMeasurements() const { return n_; } |
| float Output() const { return value_; } |
| |
| private: |
| float gain_; |
| int n_; |
| float value_; |
| }; |
| |
| } // namespace filterfw |
| } // namespace android |
| |
| #endif // ANDROID_FILTERFW_CORE_STATISTICS_H |