Re: A simple Solve gives me errors
- To: mathgroup at smc.vnet.net
- Subject: [mg132630] Re: A simple Solve gives me errors
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Thu, 24 Apr 2014 04:03:14 -0400 (EDT)
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- Delivered-to: l-mathgroup@wolfram.com
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On 4/23/14 at 4:54 AM, stevebg at roadrunner.com (Ste[hen Gray) wrote: >I want to find the center C of a circle in 3D where the plane is >defined by points p1,p2,p3. I wrote this: >eq1 = (ctr - p1).(ctr - p1) - (ctr - p2).(ctr - p2) := 0; >eq2 = (ctr - p1).(ctr - p1) - (ctr - p3).(ctr - p3) := 0; >I get errors of a type I've seen before: You cannot use SetDelayed (:=) in place of Equal (==). You get the error since SetDelayed is attempting to do precisely what it is documented to do. That is assign the value 0 to expression on the left hand side. This clearly isn't what you want and isn't something Mathematica can do. Rewrite your definitions for eq1 and eq2 replacing := with == and you should get the result you want.