Implement four-quadrant inverse tangent about jblas HOT 1 OPEN

public static FloatMatrix atan2(FloatMatrix x, FloatMatrix y){     

        FloatMatrix intermediate = sqrt(x.mul(x).add(y.mul(y)));

        FloatMatrix domainOne = atan(y.div(intermediate.add(x))).mul(2);
        FloatMatrix domainTwo = atan(intermediate.sub(x).div(y)).mul(2);

        FloatMatrix result = new FloatMatrix(x.getRows());

        for(int index : x.gt(0).findIndices()) result.put(index, domainOne.get(index));
        for(int index : x.le(0).and(y.ne(0)).findIndices()) result.put(index, domainTwo.get(index));
        for(int index : x.lt(0).and(y.eq(0)).findIndices()) result.put(index, (float) Math.PI);
        for(int index : x.eq(0).and(y.eq(0)).findIndices()) result.put(index, Float.NaN);

        return result;
    }