int f2cad::dscal_(integer *n, doublereal *da, doublereal *dx, integer *incx);
This is a simple example using Adolc and the libf2cadAdolc.a library routine dscal to compute the function   $f(a) = a \left( \begin{array}{c} 1 \\ 2 \end{array} \right)$  We check that the derivative of this function, calculated using the Adolc, satisfies   $f^{(1)} (a) = \left( \begin{array}{c} 1 \\ 2 \end{array} \right)$   // standard input output library # include <iostream> // f2cad set up for adouble # define F2CAD_USE_ADOLC // prototype for dscal # include <f2cad/dscal.hpp> int main(void) { // turn on recording of adouble operations int tag = 1; int keep = 1; trace_on(tag, keep); // independent variables int n = 1; // number of independent variables adouble a[1]; // vector of independent variables a[0] <<= 5.; // first independent variables // create data structure expected by dscal integer m = 2; adouble f[2]; f[0] = 1.; f[1] = 2.; integer incf = 1; // set f = a * f f2cad::dscal_(&m, a, f, &incf ); // dependent variables double fi; f[0] >>= fi; // first dependent variable value f[1] >>= fi; // second dependent variable value // turn off recording of adouble operations trace_off(); // set differential for a int d = 1; // order of the differential double *daMemory = new double [2 * n]; double **da = new double * [n]; int i, j; for(j = 0; j < n; j++) da[j] = daMemory + 2 * j; da[0][0] = .5; // value of a da[0][1] = 1.; // differential for a // compute differential for f double *dfMemory = new double [2 * m]; double **df = new double * [m]; for(i = 0; i < m; i++) df[i] = dfMemory + 2 * i; forward(tag, int(m), n, d, keep, da, df); // print results std::cout << "f(a) = a * (1, 2)^T" << std::endl; std::cout << "f'(a) = (" << df[0][1] << ", " << df[1][1] << ")^T" << std::endl; bool ok = df[0][1] == 1. && df[1][1] == 2.; // free allocated memory delete [] daMemory; delete [] dfMemory; delete [] da; delete [] df; if( ok ) return 0; // no error return 1; // error }