scalismo.sampling.evaluators.GaussianEvaluator.scala Maven / Gradle / Ivy
/*
* Copyright 2016 University of Basel, Graphics and Vision Research Group
*
* 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.
*/
package scalismo.sampling.evaluators
import scalismo.sampling.DistributionEvaluator
/** 1D Gaussian distribution */
case class GaussianEvaluator(mean: Double, sdev: Double) extends DistributionEvaluator[Double] {
val normalizer: Double = -0.5 * math.log(2 * math.Pi) - math.log(sdev)
/** log probability/density of sample */
override def logValue(sample: Double): Double = -0.5 * (sample - mean) * (sample - mean) / sdev / sdev + normalizer
}
object GaussianEvaluator {
/** probability density of 1D Gaussian distribution */
def logDensity(x: Double, mean: Double, sdev: Double): Double = {
-0.5 * math.log(2 * math.Pi) - math.log(sdev) - 0.5 * (x - mean) * (x - mean) / sdev / sdev
}
}