Fractional derivative

[robmio]

here is the modified program:

Code:


#cas
DerFraz(ff,pp,aa):=
//ff --> (x)->funzione
//aa: estremo inferiore dell'intergrale;
//pp grado di derivazione
BEGIN
LOCAL kappa, fnz, uu;
uu:=lname(ff)(1);
kappa:=MAX(0,CEILING(pp));
IF type(pp)==DOM_INT AND SIGN(pp)==1 THEN
kappa:=pp+1;
fnz:=(t)->((1/Gamma(kappa-pp))*
int((t-x)^(kappa-pp-1)*ff(x),x,aa,
assume(t>0 AND t>x)));
fnz:=(x)->fnz(purge(x));
ELSE
fnz:=(t)->(1/Gamma(kappa-pp))*
int((t-x)^(kappa-pp-1)*ff(x),x,aa,
assume(t>0 AND t>x));
fnz:=(x)->fnz(purge(x));
END;
IF SIGN(pp)==−1 THEN
RETURN subst(fnz(t),t,uu);
ELSE
IF pp==0 THEN
RETURN ff(uu);
ELSE
RETURN subst(diff(fnz(t),t,kappa),t,uu);
END;
END;
END;
#end