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Re: NMinimize problem: fct minimized uses FindRoot

• To: mathgroup at smc.vnet.net
• Subject: [mg123603] Re: NMinimize problem: fct minimized uses FindRoot
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Tue, 13 Dec 2011 05:39:04 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <201112101227.HAA19219@smc.vnet.net> <201112121143.GAA12817@smc.vnet.net>

On 12 Dec 2011, at 12:43, Oleksandr Rasputinov wrote:

> For example, the erroneous usage:
>
> Block[{a = 1, b = 2}, Return[a]; Return[b]]
>
> gives:
>
> Return[1]
>
> but a correct usage:
>
> Do[Block[{a = 1, b = 2}, Return[a]; Return[b]], {1}]
>
> gives (because of the enclosing Do):
>
> 1

This is not quite the whole story. For example, while the above use of Return in Block does not work, this one (in a function call) does:

f[] := Block[{a = 1, b = 2}, Return[a]; Return[b]]

f[]

1

Moreover, if you replace the Do loop in your example with a While loop, you will get:

n = 1; While[n < 10, Block[{a = 1, b = 2}, Return[a]; Return[b]]]

Return[1]

All of this is purposeful design and can be explained and justified but I don't think it's worth the bother since Mathematica has far superior means of flow control than this clumsy and arcane construct.

Andrzej 

• References:
  • NMinimize problem: fct minimized uses FindRoot
    • From: "Doug Tinkham" <dtinkham@live.ca>
  • Re: NMinimize problem: fct minimized uses FindRoot
    • From: "Oleksandr Rasputinov" <oleksandr_rasputinov@hmamail.com>