       Re: Dynamic

• To: mathgroup at smc.vnet.net
• Subject: [mg87463] Re: Dynamic
• From: dh <dh at metrohm.ch>
• Date: Fri, 11 Apr 2008 01:43:43 -0400 (EDT)
• References: <ftfeji\$bue\$1@smc.vnet.net>

```
Hi Gianluca,

whow, what stamina!

I can not explain all quircks, but what matters is:

- if you have an expression that you want dynamically updated, you must

wrap it with Dynamic. p+1 is not updated. Dynamic[p]+1 only updates p

not the sum. Therefore, you need: Dynamic[p+1].

- FullForm sort of creates an inactive print form (sorry can not explain

it better)

hop this helps, Daniel

Gianluca Gorni wrote:

> Hi!

>

> I am trying to learn how the new Dynamic features work.

>

> The following two Manipulate expressions give outputs that

> make perfect intuitive sense to me:

>

> Manipulate[q = p + 1;

>   q,

>   {p, 0, 1}]

>

> Manipulate[q = p + 1;

>   FullForm@q,

>   {p, 0, 1}]

>

> (don't keep both outputs active at the same time

> if you are short on battery power!)

>

> When I try to reproduce similar effects with

> DynamicModule, I get all sorts of different behaviours.

> Compare the following:

>

> DynamicModule[{p = 0, q},

>   q = p + 1;

>   {Slider[Dynamic@p], q}]

>

> DynamicModule[{p = 0, q},

>   q = p + 1;

>   {Slider[Dynamic@p], Dynamic@q}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p] + 1;

>   {Slider[Dynamic@p], q}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p] + 1;

>   {Slider[Dynamic@p], FullForm@q}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p] + 1;

>   {Slider[Dynamic@p], FullForm@Dynamic@q}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p] + 1;

>   {Slider[Dynamic@p], Dynamic@FullForm@q}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p + 1];

>   {Slider[Dynamic@p], q}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p + 1];

>   {Slider[Dynamic@p], q[[1, 1]]}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p + 1];

>   {Slider[Dynamic@p], q[[1, 2]]}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p + 1];

>   {Slider[Dynamic@p], Dynamic@q}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p + 1];

>   {Slider[Dynamic@p], Dynamic[q[[1, 1]]]}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p + 1];

>   {Slider[Dynamic@p], Dynamic[q[[1, 2]]]}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p + 1];

>   {Slider[Dynamic@p], FullForm@q}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p + 1];

>   {Slider[Dynamic@p], Dynamic@FullForm@q}]

>

> DynamicModule[{p = 0, q},

>   q = Dynamic[p + 1];

>   {Slider[Dynamic@p], FullForm@Dynamic@q}]

>

> Right now all I need is a few kind words of encouragement

> from somebody who has already mastered dynamic interactivity...

>

> Gianluca

>

>

```

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