SCIP in C++11 ― 1.3.4節 その3

抽象と第一級手続き

Newton法のコードや不動点探索のコードと重複する部分はバッサリ略。

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const double fixedPointOfTransform

(const function<double(double)>& g,

 const function<function<double(double)>(function<double(double)>)>&

 transform,

 const double guess)

{

    return(fixedPoint(transform(g), guess));

}

const double sqrtFixed2(const double x)

{

    return(fixedPointOfTransform([x](const double y){return(x/y);},

                                 averageDamp,1.0));

}

const double sqrtNewton2(const double x){

    return(fixedPointOfTransform

           ([x](const double y){return(square(y)-x);},

            NewtonTransform,1.0));

}

int main(int argc, char** argv)

{

    cout<<setprecision(16)<<"sqrt(2) with fixed point="

        <<sqrtFixed2(2)<<endl;

    cout<<setprecision(16)<<"sqrt(2) with Newton's method="

        <<sqrtNewton2(2.0)<<endl;

    return(0);

}

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出力

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sqrt(2) with fixed point=1.41421356237469

sqrt(2) with Newton's method=1.41421356245306