Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2007
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Re: minmum of a function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg75223] Re: [mg75126] Re: minmum of a function
  • From: skruege at gwdg.de
  • Date: Sat, 21 Apr 2007 23:05:37 -0400 (EDT)
  • References: <f014ar$8qr$1@smc.vnet.net>

Hi Jean-Marc,

Thank for your help.
I think (Head /@ t1)[[All,1]] is exactly what I need.
Probably I could simplify my definitions of function even before.
In fact, I defined

amp := fmax/f5

with fmax := FindMaximum[Sum[Integrate[f1[x], {x, i, i + a}], {i, 0, 2}],
{p, 0}] whereas f1[x_] := c + (Cos[Pi*x + p])^2
and
f5 := Integrate[f4[x], {x, 0, 2 + a}] whereas f4[x_] := c + (Cos[Pi*x +
pmax])^2 and pmax := p  /. fmax[[2]].

With (Head /@ t1)[[All,1]] I'm now able to create a list amp[a] and to
plot it.
Before your help, I managed to get the list by using 'Block' like f6 :=
Block[{a = 0.1}, amp], but it isn't elegant at all.

Regards,
Sven

> Hi Sven,
>
> (Head /@ t1)[[All,1]]
>
> will do it.
>
> Now the question is: Are you sure that the format of the list t1 is
> really the one you want? As defined (or returned by amp[a]), t1 is a
> list of expressions with _head_ of the form {aNumber, {anotherNumber *
> aRule}}. Therefore, the elements that Part sees by default are 0.1, 0.2,
> etc.
>
> In[1]:=
> t1 = {{0.270697, {0.909768*(p -> -0.15708)}}[0.1],
>      {0.270697, {0.837837*(p -> -0.314159)}}[0.2],
>      {0.653976, {0.782008*(p -> -0.471239)}}[0.3]};
>
> In[2]:=
> t1[[1]]
>
> Out[2]=
> {0.270697, {0.909768*(p -> -0.15708)}}[0.1]
>
> In[3]:=
> Head[t1[[1]]]
>
> Out[3]=
> {0.270697, {0.909768*(p -> -0.15708)}}
>
> In[4]:=
> Head[t1[[1]]][[1]]
>
> Out[4]=
> 0.270697
>
> In[5]:=
> (Head /@ t1)[[All,1]]
>
> Out[5]=
> {0.270697, 0.270697, 0.653976}
>
> You may prefer to check your function amp[] and fix it so it will return
> its results as a list of values.
>
> Regards,
> Jean-Marc
>
>



  • Prev by Date: Re: how to get the table 2
  • Next by Date: RootSum 2
  • Previous by thread: Re: minmum of a function
  • Next by thread: Re: minmum of a function