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Re: Is there ToNumber?

• To: mathgroup at smc.vnet.net
• Subject: [mg119629] Re: Is there ToNumber?
• From: Daniel Lichtblau <danl at wolfram.com>
• Date: Wed, 15 Jun 2011 07:19:52 -0400 (EDT)
• References: <isnllk$n7b$1@smc.vnet.net> <201106090945.FAA06238@smc.vnet.net> <201106141013.GAA06195@smc.vnet.net>

On 06/14/2011 05:13 AM, SigmundV wrote:
> I had imagined that applying Real to the string would make it a
> number, e.g. Real@@"1.2", but it doesn't work:
>
> In[1]:= Head[Real @@ "1.2"]
>
> Out[1]= String
>
> Of course ToExpression works as intented:
>
> In[2]:= Head[ToExpression@"1.2"]
>
> Out[2]= Real
>
> Why can't I simply change the head of a string by using Apply?

Same reason one cannot change the head of an Integer. They are atomic.

http://www.great-quotes.com/quote/1727982

In[3]:= Apply[Integer,1.0]

Out[3]= 1.

Moreover, even if String was not atomic an type, there is neither 
documentation nor functionality to suggest Real converts input to real 
numbers.

Daniel Lichtblau
Wolfram Research

• References:
  • Re: How show axes labels with AxesOrigin->{0,0,0} in 3D?
    • From: Peter Breitfeld <phbrf@t-online.de>
  • Re: Is there ToNumber?
    • From: SigmundV <sigmundv@gmail.com>