Re: Block and Module
- To: mathgroup at smc.vnet.net
- Subject: [mg15157] Re: Block and Module
- From: "A.ODA" <a-oda at muj.biglobe.ne.jp>
- Date: Wed, 16 Dec 1998 03:11:28 -0500
- Organization: BIGLOBE dial-up user
- References: <74tce8$4vs@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
David Epstein wrote in message <74tce8$4vs at smc.vnet.net>...
>Could someone explain what the difference is between Block and Module? A
>couple of easy examples would help, rather than a long theoretical
>explanation.
>
>David Epstein
>
Try these two examples.
ex. 1
Module[{PlotRange},
Plot[Sin[x],{x,0,Pi},PlotRange->{0,2}]];
ex.2
Block[{PlotRange},
Plot[Sin[x],{x,0,Pi},PlotRange->{0,2}]];
The ex.1 will stop by "Unknown option" but ex.2 will work as you
expected.
"Module" assigns new address for local variable, so the actual name of
the variable in ex.1 is PlotRange$1 or $number. However, "Block" simply
save and retrieve value of variable in the first argument. Usually,
Module and Block work same, unless you use some global variables. Most
useful technique of Block is temporal change for some global variables
which affects system defaults like RecursionLimits.
A.ODA <a-oda at muj.biglobe.ne.jp>
Kawasaki, JAPAN