CFunction* CGeneratorContext::AddFunction(const char* name)
{
CFunction* function = new CFunction();
function->SetName(name);
mFunctions.push_back(function);
return function;
}
int main()
{
// The number that the variable "x" will point to
double_complex x;
// Creates a variable named "x" and which value will be x
CVar xvar ( "x" , &x );
// Asks for a fomula depending on the variable x, e.g. "sin 2x"
char s[500]="";
printf("Enter a formula depending on the variable x:\n");
gets(s);
// Creates an operation with this formula. The operation depends on one
// variable, which is xvar ; the third argument is an array of pointers
// to variables; the previous argument is its size
CVar* vararray[1]; vararray[0]=&xvar;
COperation op ( s, 1, vararray );
// Affects (indirectly) a value to xvar
x=3;
// Printfs the value of the formula for x=3;
printf("%s = %s for x=3\n\n", op.Expr(), PrettyPrint(op.Val()) );
// Creates a function name which can be used in later functions to refer to the operation op(x)
CFunction f (op, &xvar); f.SetName("f");
// Creates a second variable named y, and a formula depending on both x and y
double_complex y;
CVar yvar ( "y" , &y );
CVar* vararray2[2]; // table of variables containing the adresses of xvar and yvar
vararray2[0]=&xvar; vararray2[1]=&yvar;
// Asks for a formula using x, y and the already-defined function f, e.g. x+f(3y)
printf("Enter a formula using x, y and the function f(x): x -> %s that you just entered, e.g. x+f(3y) :\n", op.Expr());
gets(s);
CFunction* funcarray[1]; funcarray[0]=&f;
COperation op2 ( (char*)s , 2 , vararray2 , 1, funcarray );
// vararray2 is a CVar* array with two elements
// funcarray is a CFunction* array with one element
y=5;
printf("Value for x=3, y=5 : %s\n", PrettyPrint(op2.Val()) );
// Turns the last expression into a function of x and y
CFunction g(op2, 2, vararray2); g.SetName("g");
// Here is another way to do it
double_complex z,t;
CVar zvar("z", &z), tvar("t", &t);
COperation op3,zop,top;
zop=zvar; top=tvar; // constructs, from a variable, the operation returning its value
op3=g( (zop+top, top^2) ); // Ready-to-use ; needs two pairs of ( )
// Now op3 contains the operation op2 with x replaced with z+t, and y replaced with t^2
z=5;t=7;
printf("\nLet g be the function g : x,y -> %s\n", op2.Expr());
printf("Value of %s for z=5,t=7:\n %s\n", op3.Expr(), PrettyPrint(op3.Val()) );
COperation dopdt=op3.Diff(tvar); // Computes the derivative of op3 w.r.t t
printf("Value of d/dt (g(z+t,t^2)) = %s for z=5,t=7:\n %s\n", dopdt.Expr(), PrettyPrint(dopdt.Val()) );
COperation dopdtbar=op3.DiffConj(tvar); // Computes the derivative of op3 w.r.t the conjugate of t
printf("Value of d/dtbar (g(z+t,t^2)) = %s for z=5,t=7:\n %s\n", dopdtbar.Expr(), PrettyPrint(dopdtbar.Val()) );
return 0;
}
