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MathGroup Archive 2004

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Re: Adding Vectors -- Newbie help please

  • To: mathgroup at smc.vnet.net
  • Subject: [mg52059] Re: Adding Vectors -- Newbie help please
  • From: "Steve Luttrell" <steve_usenet at _removemefirst_luttrell.org.uk>
  • Date: Tue, 9 Nov 2004 01:36:48 -0500 (EST)
  • References: <cmfc9b$7k3$1@smc.vnet.net> <cmhut5$ppb$1@smc.vnet.net> <cmklrk$jm3$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Ignore my previous reply to this message. I didn't notice that you were 
using curvilinear coordinates.

Steve Luttrell

"motz art" <music at heart.com> wrote in message 
news:cmklrk$jm3$1 at smc.vnet.net...
> Ok; but I was hoping that there is a simpler way than the
> following method  to add  two ac voltage vectors (for example):
>
>                               (220V, 225 degrees)
>                               (100V, 16 degrees)
>
> Clear[r, x, y, Theta, rect, polar]
>
> rect[r_,Theta_] := { r Cos[Theta Pi/180] , r  Sin[Theta Pi/180]}
> polar[x_, y_] := {Sqrt[x^2 + y^2], ArcTan[x, y]180/Pi}
>
> (* Input vectors here *)
> v1 := {220, 225};
> v2 := {100, 16};
>
> r1:= rect[v1[[1]], v1[[2]] ] // N;
> r2:= rect[v2[[1]], v2[[2]] ] // N;
> rt := p1 + p2
>
> polar[rt[[1]], rt[[2]]] // N
>
> This just seems so cumbersome, especially when compared to a
> scientific calculator.
>
>
>
> On Sat, 6 Nov 2004 07:36:05 +0000 (UTC), David Bailey
> <dave at Remove_Thisdbailey.co.uk> wrote:
>
>>motz art wrote:
>>> Mathematica v5: How can I input vectors in polar form and
>>> rectangular form?
>>>
>>> Example:
>>>
>>> a:= (r1, theta1) + (r2, theta2)  Polar form.
>>>
>>> b:= (re1 , j* im1) + (re2, j*im2) Rectangular form
>>>
>>> I know this should be pretty basic, but I haven't  found examples
>>> of this kind of input.
>>>
>>> I would guess it would be something like:
>>>
>>>           Polar[magnitude, phase]
>>>           Rectangular[Real, Imaginary]
>>>
>>> but, apparently not.  (This is for  electronics engineering.)
>>>
>>> Thanks for any help.
>>>
>>>
>>>
>>>
>>>
>>You can easily write a function to convert from polar to coordinate form:
>>
>>FromPolar[r_, theta_] := {r Cos[theta], r Sin[theta]}
>>
>>Note that this assumes your angles are measured in radians. Once all
>>your vectors are in coordinate form you can add/subtract then directly:
>>
>>{1,2}+(3,4}
>>
>>produces
>>
>>{4,6}
>>
>>Regards,
>>
>>David Bailey
> 



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