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MathGroup Archive 2004

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Re: Adding Vectors -- Newbie help please

  • To: mathgroup at smc.vnet.net
  • Subject: [mg52023] Re: Adding Vectors -- Newbie help please
  • From: motz art <music at heart.com>
  • Date: Sun, 7 Nov 2004 01:04:10 -0500 (EST)
  • References: <cmfc9b$7k3$1@smc.vnet.net> <cmhut5$ppb$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

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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