Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

Better Set or Set Delayed ?

• To: mathgroup at smc.vnet.net
• Subject: [mg45138] Better Set or Set Delayed ?
• From: "Jean.Pellegri" <Jean.Pellegri at wanadoo.fr>
• Date: Thu, 18 Dec 2003 06:55:14 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

phi is the function : phi[u_,v_]=u^4+v^3

For calculating the Laplacian at u=3 and v=4 ,

is better :

this ??

Laplacien2[f_][x_,y_]:=
  Module[{expr,p,q,Dpp,Dqq,subs},
    expr = f[p,q];                  (* Set *)
    Dpp=D[expr,{p,2}];
    Dqq=D[expr,{q,2}];
    subs={p->x,q->y};
    Dpp+Dqq/.subs]

Laplacien2[phi][3,4]

or this ???

Laplacien3[f_][x_,y_]:=
  Module[{g,p,q,Dpp,Dqq,subs},
    g[p_,q_] = f[p,q];                (* Set *)
    Dpp=D[g[p,q],{p,2}];
    Dqq=D[g[p,q],{q,2}];
    subs={p->x,q->y};
    Dpp+Dqq/.subs]

Laplacien3[phi][3,4]

or this ????

Laplacien4[f_][x_,y_]:=
  Module[{g,p,q,Dpp,Dqq,subs},
    g[p_,q_] := f[p,q];               (* Set Delayed *)
    Dpp=D[g[p,q],{p,2}];
    Dqq=D[g[p,q],{q,2}];
    subs={p->x,q->y};
    Dpp+Dqq/.subs]

Laplacien4[phi][3,4]

Thanks and Ciao

-- 
< Jean Pellegri >
"fortitudo mea in rota"
93100 Montreuil