[liteon]

using the above approximation of exp() and the identity:

2^x=exp(x*log(2));

it is possible to get a fixed base approximation of b^x:

@init
//base 2
b=log(2);
@sample
//example with 4 point polynomial:
x*=b;
y=x;
y*=0.189;
y+=0.612;
y*=x;
y+=0.995;
y*=x;
y+=0.975;

//x=1 -> y=2.02166035;
//x=2 -> y=4.03404514;

stable within x range [-2, 2,5]

[img]http://img233.**************/img233/9909/powlagrange.gif[/img]

performance test (100 executions per sample):
4point approximation (2^x) - 33%
inline 2^x - 75%

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lubomir