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Steepest Decent Method for Multiple Variable Functions

by Siamak Faridani

 

07 Jan 2009

Solves a multivariable unconstrained optimization method using the Steepest Decent Method

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Description

Replace your function in the code and the output will be similar to the following

Steepest Descent Method
=============
Function = -(3*x1+x2+6*x1*x2-2*(x1^2)+2*(x2^2))
Hessian......
 
                    [ 4 -6]
                    [ ]
                    [-6 -4]
Gradient......
 
                    [-3 - 6 x2 + 4 x1]
                    [ ]
                    [-1 - 6 x1 - 4 x2]
Eigen Values
[ 2*13^(1/2), 0]
[ 0, -2*13^(1/2)]
 
f(x0)=5.000000
_________________________________________
Iteration = 1
Gradient of X0
    -7
     5

X0 =
    -1
     0

X0 - alpha. gradient(X0) =
 -1+7*alpha
   -5*alpha
 
f(X0 - alpha. gradient(X0)) =
3-16*alpha+30*(-1+7*alpha)*alpha+2*(-1+7*alpha)^2-50*alpha^2
 
diff(f(X0 - alpha. gradient(X0)))/diff alpha =
-74+516*alpha
 
 
alphaval =
 
37/258
 
 

alphaval2 =

   0.143410852713178

x1 =
   0.003875968992248
  -0.717054263565892

f(x2)=-0.306202
_________________________________________
Iteration = 2
Gradient of X1
   1.317829457364341
   1.844961240310078

X1 =
   0.003875968992248
  -0.717054263565892

X1 - alpha. gradient(X1) =
    1/258-170/129*alpha
 -185/258-238/129*alpha
 
f(X1 - alpha. gradient(X1)) =
91/129+748/129*alpha-6*(1/258-170/129*alpha)*(-185/258-238/129*alpha)+2*(1/258-170/129*alpha)^2-2*(-185/258-238/129*alpha)^2
 
diff(f(X1 - alpha. gradient(X1)))/diff alpha =
-85544/16641-4624/129*alpha
 
 
alphaval =
 
-37/258
 
 

alphaval2 =

  -0.143410852713178

MATLAB release MATLAB 7.5 (R2007b)
Other requirements You may need the Symbolic toolbox based on your MATLAB version
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optimization Siamak Faridani 08 Jan 2009 13:36:15
nonlinear Siamak Faridani 08 Jan 2009 13:36:15

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