io.warp10.script.functions.TR.java Source code

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Here is the source code for io.warp10.script.functions.TR.java

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//
//   Copyright 2016  Cityzen Data
//
//   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 io.warp10.script.functions;

import io.warp10.script.NamedWarpScriptFunction;
import io.warp10.script.WarpScriptException;
import io.warp10.script.WarpScriptStack;
import io.warp10.script.WarpScriptStackFunction;

import org.apache.commons.math3.linear.RealMatrix;

/**
 * Computes the trace of a matrix
 */
public class TR extends NamedWarpScriptFunction implements WarpScriptStackFunction {

    public TR(String name) {
        super(name);
    }

    @Override
    public Object apply(WarpScriptStack stack) throws WarpScriptException {

        Object o = stack.pop();

        if (!(o instanceof RealMatrix)) {
            throw new WarpScriptException(getName() + " expects a matrix on top of the stack.");
        }

        RealMatrix matrix = (RealMatrix) o;

        stack.push(matrix.getTrace());

        return stack;
    }
}