private void bisectBacktrack( final DoubleMatrix1D p, final Function1D<DoubleMatrix1D, Double> function, final DataBundle data) { do { data.setLambda0(data.getLambda0() * 0.1); updatePosition(p, function, data); } while (Double.isNaN(data.getG1()) || Double.isInfinite(data.getG1()) || Double.isNaN(data.getG2()) || Double.isInfinite(data.getG2())); }
private void cubicBacktrack( final DoubleMatrix1D p, final Function1D<DoubleMatrix1D, Double> function, final DataBundle data) { double temp1, temp2, temp3, temp4, temp5; final double lambda0 = data.getLambda0(); final double lambda1 = data.getLambda1(); final double g0 = data.getG0(); temp1 = 1.0 / lambda0 / lambda0; temp2 = 1.0 / lambda1 / lambda1; temp3 = data.getG1() + g0 * (2 * lambda0 - 1.0); temp4 = data.getG2() + g0 * (2 * lambda1 - 1.0); temp5 = 1.0 / (lambda0 - lambda1); final double a = temp5 * (temp1 * temp3 - temp2 * temp4); final double b = temp5 * (-lambda1 * temp1 * temp3 + lambda0 * temp2 * temp4); double lambda = (-b + Math.sqrt(b * b + 6 * a * g0)) / 3 / a; lambda = Math.min( Math.max(lambda, 0.01 * lambda0), 0.75 * lambda1); // make sure new lambda is between 1% & 75% of old value data.swapLambdaAndReplace(lambda); updatePosition(p, function, data); }