HELP!! Using Solve for Simultaneous Eqns.
- To: mathgroup at smc.vnet.net
- Subject: [mg8338] HELP!! Using Solve for Simultaneous Eqns.
- From: sstadler at holadayinc.com (Steve Stadler)
- Date: Sun, 24 Aug 1997 13:24:54 -0400
- Organization: Goldengate Internet Services, Inc.
- Sender: owner-wri-mathgroup at wolfram.com
I am using these two equations:
convert={power==10voltage×current,voltage==r×current};
to define the conversion from mW/cm^2 to V/m and A/m.
If I use the Solve function for the simultaneous equations with all of
the variables in the list of variables to solve for, I get a message:
Solve::"svars": "Equations may not give solutions for all \"solve\"
variables.
and the result contains two of the four variables in the equations.
I can force the results I am looking for by using three Solve
statements, defining the two variables I know, listing the output
variables I need, in the appropriate statement, and look at the
output, But I think I shouldn't have to do that.
Reduce[convert,{power,voltage,current,r}];
temp=Solve[convert,{power,voltage}];
temp/.{current -->2.82091,r -->377}//N
temp=Solve[convert,{power,current}];
temp/.{voltage -->1063.48,r -->377}//N
temp=Solve[convert,{voltage,current}];
temp/.{power -->30000,r -->377}//N
I would like to be able to define two of the variables and display the
solved variables with one Solve statement.
temp=Solve[convert,{power,voltage,current,r}];
temp/.{current -->2.82091,r -->377}//N
or
temp/.{voltage -->1063.48,r -->377}//N
or
temp/.{power -->30000,r -->377}//N
Thanks for any suggestions!