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MathGroup Archive 2001

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Re: Complex Number Simultaneous Equation 2 Unknowns

  • To: mathgroup at smc.vnet.net
  • Subject: [mg31534] Re: Complex Number Simultaneous Equation 2 Unknowns
  • From: "Avraham Shinnar" <as1619 at columbia.edu>
  • Date: Fri, 9 Nov 2001 06:13:43 -0500 (EST)
  • Approved: Steven M. Christensen <steve@smc.vnet.net>, Moderator
  • Organization: Columbia University
  • References: <9sdnp2$6gs$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

The primary problem wich is causing the error, is the use of =.  = means
assignment, == means a test for equality.
The FullForm of [((2 + 4\[ImaginaryI])*a) + ((1 + \[ImaginaryI])*b) is:
 Plus[Times[Complex[2, 4], a], Times[Complex[1, 1], b]].
So you are trying to assign something to the Plus function, which is
protected.

Some other problems: if you want to specify more then one equation, you have
to either put them in a list, or use and (&& or \[And]) to combine them.

option 1) Solve [{((2 + 4\[ImaginaryI])*a) + ((1 + \[ImaginaryI])*b) == (118
+
24\[ImaginaryI]), ((1 + \[ImaginaryI])* a) + ((3 + \[ImaginaryI])*
            b) == (110 + \[ImaginaryI]0)}, {a, b}]

option 2) Solve [((2 + 4\[ImaginaryI])*a) + ((1 + \[ImaginaryI])*b) == (118
+
24\[ImaginaryI]) && ((1 + \[ImaginaryI])* a) + ((3 + \[ImaginaryI])*
            b) == (110 + \[ImaginaryI]0), {a, b}]

note: you also accidenly used curly braces where you did not mean to:  {110
+ \[ImaginaryI]0}.
These should be replaced by parenthesis (as i did).
In general () are used to specify the order of operations, {} delineate a
list, and [] is used for a function application: f[x].

If you want to enter a \[ImaginaryJ], type in esc jj esc.  note that output
will still contain \[ImaginaryI]), since internally they are both Complex[0,
1], and \[ImaginaryI]) is the default output form of this.


"Removethisspamtrap_Martin Evans_ and this one too" <mcemail at dial.pipex.com>
wrote in message news:9sdnp2$6gs$1 at smc.vnet.net...
> I've a simultaneous linear equation with complex numbers i'd like to
> put through Mathematica (I'm assuming this is possible!)
>
>
>
> Solve [((2 + 4\[ImaginaryI])*a) + ((1 + \[ImaginaryI])*b) = (118 +
>         24\[ImaginaryI]),
>
> ((1 + \[ImaginaryI])* a) + ((3 + \[ImaginaryI])*
>           b) = {110 + \[ImaginaryI]0},
>
> {a, b}]
>
> (all on one line but split for some sort of clarity here)
>
>
> I get this as the output:
>
> Set::"write": "Tag \!\(Plus\) in \!\(\(\(\(\((2 + \(\(4\\ \
> \[ImaginaryI]\)\))\)\)\\ a\)\) + \(\(\(\((1 + \[ImaginaryI])\)\)\\
> b\)\)\) is \
> Protected."
>
> Set::"write": "Tag \!\(Plus\) in \!\(\(\(\(\((1 + \[ImaginaryI])\)\)\\
> a\)\) \
> + \(\(\(\((3 + \[ImaginaryI])\)\)\\ b\)\)\) is Protected."
>
> General::"ivar": "\!\(110 + \[ImaginaryI]0\) is not a valid variable."
>
> Solve[118 + 24 \[ImaginaryI], {110 + \[ImaginaryI]0}, {a, b}]
>
> Any ideas as to what i'm doing wrong as the error messages don't make
> it obvious (at least to me as a 4 day old user!!)
>
> Also I seem to HAVE to use the esc ii esc where i would prefer to use
> lower case J (as an electrical eng) is there something special that
> needs to be done to use lower case J as in the help files it appears
> to be in bold
>
>
> --
>




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