Pointer to function type

[lmd141]

Hi there, I'm fairly new to C++ and have begun working with pointers. I wish to create am array called sigmaf_point that reads data from a text file. I have managed to get that working, but when it comes to using this pointer I come across some problems. The array is created as such:

double sigma [5];
double *sigmaf_point = sigma;

void read(double *&sigmaf_point)
            
            string s;

            ifstream Dfile;
            std::stringstream out;

			out << 1;
            s = out.str() + ".TXT";
            Dfile.open (s.c_str());
			
			if (Dfile.fail())
            {
                return;
            }
for (int i=0; i<1; i++)
			{
* * * * * * Dfile >> sigmaf_point[i];
			}
	    }

I then create a coordinate system inside the main file, as the program I am writing is about modelling the movement of atoms, which requires you to know the coordinates:

int main();
double **coords_fluid = new double*[5000];
for (int i = 0; i < n_atoms_methane; i++)
{
	coords_fluid[i] = new double[4];
}

Now, the problem arises when I want to calculate a new variable as so:

for (int i = 0; i <= n_atoms-1; i++)
    {   
		
		    sf1=sigmaf_point(coords_fluid[i][3]);
    }

I get the error C2064: term does not evaluate to a function taking 1 arguments, and a red line under sigmaf_point that says it must be pointer to function type. I am a bit confused about this. Any help would be great.