void derives( float x, float y [], float dydx []) {dydx[ 1] = y[ 2]; dydx[ 2] = - 0. 8* x* y[ 2] - sin( x) * y[ 1];}
void derives(float x, float y[], float dydx[]) {dydx[1] = y[2]; dydx[2] = -0.8*x*y[2] - sin(x)*y[1];}