Re: Why Evaluate[Defer[1+1]] does not return 2 ?
- To: mathgroup at smc.vnet.net
- Subject: [mg110942] Re: Why Evaluate[Defer[1+1]] does not return 2 ?
- From: "David Park" <djmpark at comcast.net>
- Date: Tue, 13 Jul 2010 05:26:15 -0400 (EDT)
I think that Defer is intended for something like the following:
{PasteButton[1 + 1], PasteButton[Defer[1 + 1]]}
Evaluate, use the second button, and then evaluate the pasted result.
David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/
From: Nasser M. Abbasi [mailto:nma at 12000.org]
I am a little confused about Defer:
r = Defer[1 + 1]
Out[106]= 1 + 1
Evaluate[r]
Out[109]= 1 + 1
But help says:
"Defer[expr] returns an object which remains unchanged until it is
explicitly supplied as Mathematica input, and evaluated using
Shift+Enter, Evaluate in Place, etc. "
Isn't typing Evaluate[r] the same as Evaluate in Place mentioned above?
?Evaluate
"Evaluate[expr]
causes expr to be evaluated even if it appears as the argument of a
function whose attributes specify that it should be held unevaluated."
Isn't "r" above is the object in question whose value is 1+1?
Actually, typing "r" itself, (same as typing Evaluate[r]) does return
"1+1".
In[117]:= r
Out[117]= 1 + 1
I think I know what is the problem now, I am going by that "r" is the
expression whose value is "1+1". I think this is the problem. "r" is not
the expression, it is "1+1" which is the expression. "r" is just another
name for Defer[1+1]. Am i getting close?
--Nasser