Re: question on changing 'type' of numbers

• To: mathgroup at smc.vnet.net
• Subject: [mg69484] Re: question on changing 'type' of numbers
• From: dh <dh at metrohm.ch>
• Date: Thu, 14 Sep 2006 06:54:54 -0400 (EDT)
• References: <ee8h72\$j38\$1@smc.vnet.net>

Hi Nasser ,

I believe the answer is that 0.1 is an atom not an expression.

The Help says:"Head[expr] gives the head of expr"

Head[atom] seems to give the type of the atom.

Integer[0.1] is an expression, namely the function Integer with the

argument 0.1. As there is no such function defined, the expression is

not further evaluated.

Daniel

Nasser Abbasi wrote:

> I think of a the Head of expression as its 'type'.

>

> One is supposed to be able to use Apply[f,expr] to change head of expression

> to f.

>

> But Why can't I use this to change the head of a Real number to Integer?

>

> In[122]:=

> Remove["Global`*"]

> x = 0.1

>            -------------->Real

> Apply[Integer,x]

>         ------------------->Real. I was expecting Intger

> x = Integer[x]

>       ----------------> Now it says Integer

>

> any idea?

>

> ofcourse the question as to what should happen to the value of the variable

> if for example I change the head of 0.5 from Real to Integer is another

> matter. It seems in this case x remained 0.1 but only the head said Integer

>

> x

> ----->Integer[0.1]

>

> Now sure what the above really means :)

>

> Nasser

>

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