Re: Function that requires a function as an argument (brent_find_minima)?

Victor Bazarov <>
Mon, 06 Jul 2009 14:00:54 -0400
Markus S wrote:

On 2009-07-06 19:05:24 +0200, Victor Bazarov <>

Markus S wrote:

I try to use a function that minimizes another function (namely from
the Boost library: brent_find_minima). When I provide the function to
be minized at the very top level (ie, in the .cpp file) and call
brent_find_minima from the main block, it works fine but when I
create a class and define the function to be minimized in there (and
also call brent_find_minima in another function in that class), I get
this error during compilation:
error: argument of type double (Testclass::)(double) does not match
double (Testclass::*)(double)

I had invoked brent_find_minima with this line (which works when
called in main);
std::pair<double, double> result =
boost::math::tools::brent_find_minima(TrickyF, min, max, bits);

I started with this example:



The sample code was essentially in that linked file but to be verbose
here comes a minimal set of files, compiled with bjam (Jamroot file at
the bottom) using the boost 1.39 library both on Mac OS X 10.5.7 (Intel)
and on Debian (4.0, I think). The error message is the same on both
systems. Everything compiles and runs fine until I make the call to
brent_find_minima in active (ie, uncomment it).

There is a difference between a function and a non-static member
function, especially AFA conversion to a function pointer is concerned.
  A stand-alone function can be converted to a pointer-to-function
transparently. A member function has to be wrapped and the hidden first
argument (the object for which the member function is called) has to be
provided somehow. See 'bind1st' and 'memfun' templates.

#include <boost/math/tools/minima.hpp>
#include "Testclass.h"
using namespace std;

double TrickyFunction(double x)
    return (x-5.0);

int main()
    double min = 0.0001;
    double max = 1.0;
    int bits = 50;
    std::pair<double, double> result =
boost::math::tools::brent_find_minima(TrickyFunction, min, max, bits);
    return 0;

#ifndef Testclass_h
#define Testclass_h Testclass_h

using namespace std;

class Testclass
   double TrickyF(double x);
   void CallTrickyF();
#include "Testclass.h"
#include <boost/math/tools/minima.hpp>

Testclass::Testclass() {}
Testclass::~Testclass() {}

 double Testclass::TrickyF(double x)
   return (x-5.0);
 void Testclass::CallTrickyF()
    double temp = 5.0;
     double min = 0.0001;
    double max = 1.0;
    int bits = 50;
// std::pair<double, double> result =
boost::math::tools::brent_find_minima(TrickyF, min, max, bits);

exe testbrent : TestBrent.cpp
    : <include>.
    : <include>/usr/local/include/boost-1_39/

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