My Math Forum  

Go Back   My Math Forum > Math Forums > Math Software

Math Software Math Software - Mathematica, Matlab, Calculators, Graphing Software


Thanks Tree1Thanks
  • 1 Post By romsek
Reply
 
LinkBack Thread Tools Display Modes
August 6th, 2017, 04:36 PM   #1
Senior Member
 
SenatorArmstrong's Avatar
 
Joined: Nov 2015
From: Alabama

Posts: 127
Thanks: 15

Math Focus: Geometry, Trigonometry, Calculus
Solve feature mathematica

I have been using the Solve feature in mathematica to solve the system of equations for me when using Lagrange Multipliers. It has been a great way to check my work, but now I just began adding another Lagrange multiplier, and now mathematica is not giving me anything for an output. Perhaps I am missing something small here?

Solve[{
x^2 + y^2 - 2 == 0,
x + z - 1 == 0,
Grad[x + y + z, {x, y, z}] ==
L1 Grad[x^2 + y^2 - 2, {x, y}] +
L2 Grad[x + z - 1, {x, z}]
}]

I also tried

Solve[{
x^2 + y^2 - 2 == 0,
x + z - 1 == 0,
Grad[x + y + z, {x, y, z}] ==
L1 Grad[x^2 + y^2 - 2, {x, y,z}] +
L2 Grad[x + z - 1, {x,y, z}]
}]

and still no cigar. Any ideas?

Huge thanks!

Jacob
SenatorArmstrong is offline  
 
August 6th, 2017, 08:27 PM   #2
Senior Member
 
romsek's Avatar
 
Joined: Sep 2015
From: CA

Posts: 1,300
Thanks: 664

you need to include the multipliers L1 and L2 in the solve for list.

Mathematica is pretty picky about wanting the equation list and the solve for list to have the same length.
Thanks from SenatorArmstrong
romsek is offline  
August 8th, 2017, 09:04 PM   #3
Newbie
 
Joined: Aug 2017
From: Vancouver

Posts: 1
Thanks: 0

Code:
Simplify[{
x^2 + y^2 - 2 == 0,
x + z - 1 == 0,
Grad[x + y + z, {x, y, z}] ==
L1 Grad[x^2 + y^2 - 2, {x, y}] +
L2 Grad[x + z - 1, {x, z}]
}]
shows the third equation is False, so it thinks there can be no solution to that.

Code:
Reduce[{
x^2 + y^2 - 2 == 0,
x + z - 1 == 0, 
Grad[x + y + z, {x, y, z}] == 
L1 Grad[x^2 + y^2 - 2, {x, y, z}] + 
L2 Grad[x + z - 1, {x, y, z}]}, {x, y, z}]
but not Solve, does find L1, L2, x, y, z to satisfy that.

Notice that I did include the list of variables for it to find.
Bills is offline  
Reply

  My Math Forum > Math Forums > Math Software

Tags
feature, mathematica, solve



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Logarithm feature life24 Elementary Math 2 March 31st, 2016 04:21 AM
kernel properties and feature maps akerman Linear Algebra 4 November 13th, 2015 07:41 AM
Feature of binomials McPogor Number Theory 4 September 27th, 2013 07:03 AM





Copyright © 2017 My Math Forum. All rights reserved.