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Groups > comp.soft-sys.math.mathematica > #1669 > unrolled thread

Trignometric rules

Started byChelly <chelly85086@gmail.com>
First post2011-04-14 09:00 +0000
Last post2011-04-16 11:34 +0000
Articles 3 — 2 participants

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  Trignometric rules Chelly <chelly85086@gmail.com> - 2011-04-14 09:00 +0000
    Re: Trignometric rules Peter Pein <petsie@dordos.net> - 2011-04-15 07:56 +0000
      Re: Trignometric rules Peter Pein <petsie@dordos.net> - 2011-04-16 11:34 +0000

#1669 — Trignometric rules

FromChelly <chelly85086@gmail.com>
Date2011-04-14 09:00 +0000
SubjectTrignometric rules
Message-ID<io6d3h$drj$1@smc.vnet.net>
I have an expression as hsown below

tt = -4 k1^2 v^2 \[Epsilon]1^2 \[Epsilon]c^2 Cos[2 d1 + d2 + d3] - 
   2 k1 k2 u^2 \[Epsilon]1 Cos[d1 + d2 - \[Phi]b - \[Phi]r] + 
   2 k1^2 v^2 \[Epsilon]1^2 \[Epsilon]c^2 Cos[
     2 d1 + d2 + d3 - \[Phi]b - \[Phi]r] + 
   2 k1^3 k2 v^2 \[Epsilon]1^3 \[Epsilon]c^2 Cos[
     d1 + d3 + \[Phi]b + \[Phi]r] + 
   2 k1^2 u^2 \[Epsilon]1^2 Cos[2 d1 + d2 + d3 + \[Phi]b + \[Phi]r] - 
   2 k1^2 v^2 \[Epsilon]1^2 \[Epsilon]c^2 Cos[
     2 d1 + d2 + d3 + \[Phi]b + \[Phi]r];

I'd like to replace any term containing Cos[+/- phib + x_]  with 2 Sin [+/-phib] Sin[x]. How do I go about doing it.

Thanks
Chelly

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#1698

FromPeter Pein <petsie@dordos.net>
Date2011-04-15 07:56 +0000
Message-ID<io8tn0$qam$1@smc.vnet.net>
In reply to#1669
Am 14.04.2011 11:00, schrieb Chelly:
> I have an expression as hsown below
>
> tt = -4 k1^2 v^2 \[Epsilon]1^2 \[Epsilon]c^2 Cos[2 d1 + d2 + d3] -
>     2 k1 k2 u^2 \[Epsilon]1 Cos[d1 + d2 - \[Phi]b - \[Phi]r] +
>     2 k1^2 v^2 \[Epsilon]1^2 \[Epsilon]c^2 Cos[
>       2 d1 + d2 + d3 - \[Phi]b - \[Phi]r] +
>     2 k1^3 k2 v^2 \[Epsilon]1^3 \[Epsilon]c^2 Cos[
>       d1 + d3 + \[Phi]b + \[Phi]r] +
>     2 k1^2 u^2 \[Epsilon]1^2 Cos[2 d1 + d2 + d3 + \[Phi]b + \[Phi]r] -
>     2 k1^2 v^2 \[Epsilon]1^2 \[Epsilon]c^2 Cos[
>       2 d1 + d2 + d3 + \[Phi]b + \[Phi]r];
>
> I'd like to replace any term containing Cos[+/- phib + x_]  with 2 Sin [+/-phib] Sin[x]. How do I go about doing it.
>
> Thanks
> Chelly
>

Hi Chelly,

use pattern matching:

tt /. Cos[pb:(s_. \[Phi]b /; Abs[s] == 1) + x_.] :> 2 Sin[pb] Sin[x]

Peter

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#1714

FromPeter Pein <petsie@dordos.net>
Date2011-04-16 11:34 +0000
Message-ID<iobut1$bci$1@smc.vnet.net>
In reply to#1698
Am 15.04.2011 09:56, schrieb Peter Pein:
> Am 14.04.2011 11:00, schrieb Chelly:
>> I have an expression as hsown below
>>
>> tt = -4 k1^2 v^2 \[Epsilon]1^2 \[Epsilon]c^2 Cos[2 d1 + d2 + d3] -
>>      2 k1 k2 u^2 \[Epsilon]1 Cos[d1 + d2 - \[Phi]b - \[Phi]r] +
>>      2 k1^2 v^2 \[Epsilon]1^2 \[Epsilon]c^2 Cos[
>>        2 d1 + d2 + d3 - \[Phi]b - \[Phi]r] +
>>      2 k1^3 k2 v^2 \[Epsilon]1^3 \[Epsilon]c^2 Cos[
>>        d1 + d3 + \[Phi]b + \[Phi]r] +
>>      2 k1^2 u^2 \[Epsilon]1^2 Cos[2 d1 + d2 + d3 + \[Phi]b + \[Phi]r] -
>>      2 k1^2 v^2 \[Epsilon]1^2 \[Epsilon]c^2 Cos[
>>        2 d1 + d2 + d3 + \[Phi]b + \[Phi]r];
>>
>> I'd like to replace any term containing Cos[+/- phib + x_]  with 2 Sin [+/-phib] Sin[x]. How do I go about doing it.
>>
>> Thanks
>> Chelly
>>
>
> Hi Chelly,
>
> use pattern matching:
>
> tt /. Cos[pb:(s_. \[Phi]b /; Abs[s] == 1) + x_.] :>  2 Sin[pb] Sin[x]
>
> Peter
>

Oops! Of course:

tt /. Cos[pb:(s_. \[Phi]b /; Abs[s] == 1) + x_.] :>  2 Sin[s pb] Sin[x]

sorry,
Peter

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