org.nd4j.linalg.api.ops.impl.transforms.ATan2 Maven / Gradle / Ivy
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* Copyright (c) 2015-2018 Skymind, Inc.
*
* This program and the accompanying materials are made available under the
* terms of the Apache License, Version 2.0 which is available at
* https://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.
*
* SPDX-License-Identifier: Apache-2.0
******************************************************************************/
package org.nd4j.linalg.api.ops.impl.transforms;
import lombok.val;
import org.nd4j.autodiff.samediff.SDVariable;
import org.nd4j.autodiff.samediff.SameDiff;
import org.nd4j.imports.NoOpNameFoundException;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.api.ops.BaseTransformOp;
import org.nd4j.linalg.api.ops.DynamicCustomOp;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
/**
* Arc Tangent elementwise function
*
* @author Adam Gibson
*/
public class ATan2 extends BaseDynamicTransformOp {
public ATan2(SameDiff sameDiff, SDVariable y, SDVariable x) {
super(sameDiff, new SDVariable[] {y, x} ,false);
}
public ATan2() {}
@Override
public String opName() {
return "tf_atan2";
}
@Override
public String onnxName() {
throw new NoOpNameFoundException("No onnx op opName found for " + opName());
}
@Override
public String tensorflowName() {
return "Atan2";
}
@Override
public List doDiff(List i_v) {
//Let z=atan2(r), with r=y/x
//dz/dr = 1/(r^2+1), dr/dy = 1/x, dr/dx = -y/x^2
SDVariable y = larg();
SDVariable x = rarg();
/* SDVariable r = y.div(x);
SDVariable dOutdr = f().square(r).add(1.0).rdiv(1.0);
SDVariable drdy = x.rdiv(1.0);
SDVariable drdx = f().neg(y).div(f().square(x));
SDVariable xGrad = dOutdr.mul(drdx).mul(i_v.get(0));
SDVariable yGrad = dOutdr.mul(drdy).mul(i_v.get(0));
*/
val xGrad = f().neg(y.div(x.pow(2).add(y.pow(2)))).mul(i_v.get(0));
val yGrad = x.div(x.pow(2).add(y.pow(2))).mul(i_v.get(0));
return Arrays.asList(yGrad, xGrad);
}
}