Programming and Graphics

112 Introduction to C++ Programming and Graphics

#include <iostream>

using namespace std;

const int n=2;

void trace (double[][n], double&);

//---------------- main -----------------

int main()

{

double a[n][n] ={{0.1, 0.2},{0.9, 0.5}};

double Trace;

trace (a, Trace);

cout << "Trace: " << Trace << endl ;

return 0;

}

//---------------- trace -----------------

void trace (double a[][n], double& Trace)

{

Trace= 0.0;

for(int i=0; i<=n-1; i++)

{

Trace = Trace + a[i][i];

}

}

Running the core prints on the screen:

Trace: 0.6

An alternative implementation of thetracefunction that passes the trace
through the function return is:

double trace (double a[][n])

{

Trace=0.0;

for(int i=1; i<=n-1; i++)

{

Trace = Trace + a[i][i];

}

return Trace;

}

In this case, the function call is:

double Trace = trace (double a[][n]);