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<!--哈哈我是注释,:Student answers and discussions for [[QE2013_AC-3_ECE580-1|Part 1]],[[QE2013_AC-3_ECE580-2|2]],[[QE2013_AC-3_ECE580-3|3]],[[QE2013_AC-3_ECE580-4|4]],[[QE2013_AC-3_ECE580-5|5]]不会在浏览器中显示。-->
 
  
 
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<center> <math> x_{1} \geq 0 </math>, <math> x_{2} \geq 0 </math>. </center> <br/>
 
<center> <math> x_{1} \geq 0 </math>, <math> x_{2} \geq 0 </math>. </center> <br/>
 
Convert the above linear program into standard form and find an initial basic feasible solution for the program in standard form. <br/>
 
Convert the above linear program into standard form and find an initial basic feasible solution for the program in standard form. <br/>
 
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2.(20 pts)  
 
2.(20 pts)  
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<center><math> f= 6x_{1}^{2}+2x_{2}^{2}-5 </math></center> <br/>
 
<center><math> f= 6x_{1}^{2}+2x_{2}^{2}-5 </math></center> <br/>
 
starting from an arbitrary initial condition <math>x^{(0)} \in \mathbb{R}^{n}</math>
 
starting from an arbitrary initial condition <math>x^{(0)} \in \mathbb{R}^{n}</math>
 
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<center><math> f(x_{1}, x_{2})=\frac{1}{(x_{1}-2)^{2} + (x_{2}+1)^{2}+3} </math></center><br>
 
<center><math> f(x_{1}, x_{2})=\frac{1}{(x_{1}-2)^{2} + (x_{2}+1)^{2}+3} </math></center><br>
 
locally convex, concave, or neither in the neighborhood of the point <math> [2 -1]^{T} </math>? Justify your answer by giving all the details of your argument.
 
locally convex, concave, or neither in the neighborhood of the point <math> [2 -1]^{T} </math>? Justify your answer by giving all the details of your argument.
 
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<center>subject to <math> x_{1}+x_{2}+x_{3}=1 </math> </center><br>
 
<center>subject to <math> x_{1}+x_{2}+x_{3}=1 </math> </center><br>
 
<center><math> x_{1}+x_{2}-x_{3}=0 </math></center><br>
 
<center><math> x_{1}+x_{2}-x_{3}=0 </math></center><br>
 
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:'''Click [[2016AC-3-4|here]] to view student [[2016AC-3-4|answers and discussions]]'''
 
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5. (20 pts) Solve the following optimization problem:<br/>
 
5. (20 pts) Solve the following optimization problem:<br/>
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<center>subject to <math>x_{1}+x_{2} \leq 2</math></center><br>
 
<center>subject to <math>x_{1}+x_{2} \leq 2</math></center><br>
 
<center><math> x_{1}+2x_{2} \leq 3 </math></center>
 
<center><math> x_{1}+2x_{2} \leq 3 </math></center>
 
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Revision as of 14:31, 19 February 2019


ECE Ph.D. Qualifying Exam

Automatic Control (AC)

Question 3: Optimization

August 2016




1.(20 pts) Considern the following linear program,

minimize $ 2x_{1} + x_{2} $,

subject to $ x_{1} + 3x_{2} \geq 6 $

$ 2x_{1} + x_{2} \geq 4 $

$ x_{1} + x_{2} \leq 3 $

$ x_{1} \geq 0 $, $ x_{2} \geq 0 $.

Convert the above linear program into standard form and find an initial basic feasible solution for the program in standard form.

Click here to view student answers and discussions

2.(20 pts)

  • (15 pts) FInd the largest range of the step-size, $ \alpha $, for which the fixed step gradient descent algorithm is guaranteed to convege to the minimizer of the quadratic function
$ f = \frac{1}{2} x^{T}Qx - b^{T}x $

starting from an arbitary initial condition $ x^{(0)} \in \mathbb{R}^{n} $, where $ x \in \mathbb{R}^{n} $, and $ Q = Q^{T} > 0 $.

  • (5 pts) Find the largest range of the step size, $ \alpha $, for which the fixed step gradient descent algorithm is guaranteed to converge to the minimizer of the quadratic function
$ f= 6x_{1}^{2}+2x_{2}^{2}-5 $

starting from an arbitrary initial condition $ x^{(0)} \in \mathbb{R}^{n} $

Click here to view student answers and discussions

3. (20 pts) Is the function

$ f(x_{1}, x_{2})=\frac{1}{(x_{1}-2)^{2} + (x_{2}+1)^{2}+3} $

locally convex, concave, or neither in the neighborhood of the point $ [2 -1]^{T} $? Justify your answer by giving all the details of your argument.

Click here to view student answers and discussions

4. (20 pts) Solve the following optimization problem:

optimize $ x_{1}x_{2} $

subject to $ x_{1}+x_{2}+x_{3}=1 $

$ x_{1}+x_{2}-x_{3}=0 $

Click here to view student answers and discussions

5. (20 pts) Solve the following optimization problem:

maximize $ 14x_{1}-x_{1}^{2}+6x_{2}-x_{2}^{2}+7 $

subject to $ x_{1}+x_{2} \leq 2 $

$ x_{1}+2x_{2} \leq 3 $
Click here to view student answers and discussions



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