Example (vi)

Definitions of Gaussian #1

μ1 = {0, 2} ; Σ1 = DiagonalMatrix[{1, 2}] ;

Definition of Gaussian #2

μ2 = {2, 0} ; Σ2 = DiagonalMatrix[{2, 1}] ;

Desired plot range

prLocal = {{-7, 7}, {-7, 7}} ;

Log likelihood of first Gaussian

lp1 = logpdf[μ1, Σ1] ;  lp1 // TraditionalForm

-x^2/2 - y^2/4 + y - log(π) - (3 log(2))/2 - 1

Log likelihood of second Gaussian

lp2 = logpdf[μ2, Σ2] ; lp2 // TraditionalForm

-x^2/4 + x - y^2/2 - log(π) - (3 log(2))/2 - 1

Decision boundary

Simplify[lp1 - lp2  0]   // TraditionalForm

1/4 (-x^2 - 4 x + y (y + 4)) == 0

View Gaussians

ShowTwoGaussianPDFs[Exp[lp1 // N], Exp[lp2 // N], prLocal, x, y, yS, imSize] ;

[Graphics:../HTMLFiles/index_91.gif]

View decision boundary

ShowDecisionBoundary[μ1, Σ1, μ2, Σ2, prLocal, classColors, {data1Color, data2Color}, yS] ;

[Graphics:../HTMLFiles/index_93.gif]


Created by Mathematica  (September 8, 2003)