Adam Hardy a écrit :
> Adam Hardy on 29/05/08 11:18, wrote:
>> [EMAIL PROTECTED] on 29/05/08 10:24, wrote:
>>> In the previous message, I called twr what was really twrPrime, and I
>>> used a too slow method to compute it with a double loop. Here is a
>>> much simpler and faster way to compute this derivative:
>>>
>>> public class TwrDerivative implements UnivariateRealFunction {
>>>
>>> private final double[] a;
>>>
>>> public TwrDerivative(double[] pl, double[] b) {
>>> a = new double[pl.length];
>>> for (int i = 0; i < a.length; ++i) {
>>> a[i] = pl[i] / b[i];
>>> }
>>> }
>>>
>>> public double value(double f) {
>>> double twr = 1;
>>> double twrPrime = 0;
>>> for (int i = 0; i < a.length; ++i) {
>>> double factor = 1 + a[i] * f;
>>> twrPrime = twrPrime * factor + twr * a[i];
>>> twr *= factor;
>>> }
>>> return twrPrime;
>>> }
>>>
>>> }
>
> By the way, why do you call the gradient result 'prime'?
It is a reference to the ' character. It is a classical notation in
math. See the corresponding article in Mathworld:
http://mathworld.wolfram.com/Prime.html
This has nothing to do with prime numbers.
Luc
>
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