Class QuadFun

test/com/winvector/opt/imp/TestOpt.java:46–76

	}
	
	private static final class QuadFun implements VectorFn {
		public final double sign;
		public final double[] x0;
		
		public QuadFun(final double[] x0, final double sign) {
			this.x0 = x0;
			this.sign = sign;
		}
		
		@Override
		public int dim() {
			return x0.length;
		}

		@Override
		public VEval eval(final double[] x, final boolean wantGrad, final boolean wantHessian) {
			final int n = x0.length;
			final VEval r = new VEval(x,wantGrad,wantHessian);
			for(int i=0;i<n;++i) {
				final double diff = x[i]-x0[i];
				r.fx += sign*diff*diff;
				if(wantGrad) {
					r.gx[i] = sign*2.0*diff;
				}
				if(wantHessian) {
					r.hx[i][i] = sign*2.0;
				}
			}
			return r;
		}
	}
	
	public void testMax() {
		final QuadFun f = new QuadFun(new double[] {0.2, -.62, 110.1, 11.1},-1.0);