Hi,
I think the bivariate normal probability distribution function
implementation in Matplotlib is buggy. See the example code below, and
note that the change in the x directions and the y directions is not
uniform as it should be.
The implementation (in mlab.py) is appended.
Faheem.
***************************************************************************
minx, maxx = 0, 13
miny, maxy = 0, 13
X, Y = pylab.meshgrid(range(minx, maxx), range(miny, maxy))
conc = 1000*pylab.bivariate_normal(X, Y, sigmax=5.0, sigmay=5.0, sigmaxy=0,
mux=6, muy=6)
[[ 0.08 0.11 0.13 0.15 0.16 0.17 0.17 0.17 0.16 0.15 0.13 0.11 0.08]
[ 0.25 0.32 0.38 0.44 0.48 0.51 0.52 0.51 0.48 0.44 0.38 0.32 0.25]
[ 0.63 0.78 0.93 1.07 1.19 1.26 1.29 1.26 1.19 1.07 0.93 0.78 0.63]
[ 1.26 1.57 1.88 2.16 2.39 2.54 2.59 2.54 2.39 2.16 1.88 1.57 1.26]
[ 2.08 2.59 3.1 3.56 3.94 4.18 4.27 4.18 3.94 3.56 3.1 2.59 2.08]
[ 2.8 3.49 4.18 4.81 5.32 5.65 5.76 5.65 5.32 4.81 4.18 3.49 2.8 ]
[ 3.1 3.86 4.62 5.32 5.88 6.24 6.37 6.24 5.88 5.32 4.62 3.86 3.1 ]
[ 2.8 3.49 4.18 4.81 5.32 5.65 5.76 5.65 5.32 4.81 4.18 3.49 2.8 ]
[ 2.08 2.59 3.1 3.56 3.94 4.18 4.27 4.18 3.94 3.56 3.1 2.59 2.08]
[ 1.26 1.57 1.88 2.16 2.39 2.54 2.59 2.54 2.39 2.16 1.88 1.57 1.26]
[ 0.63 0.78 0.93 1.07 1.19 1.26 1.29 1.26 1.19 1.07 0.93 0.78 0.63]
[ 0.25 0.32 0.38 0.44 0.48 0.51 0.52 0.51 0.48 0.44 0.38 0.32 0.25]
[ 0.08 0.11 0.13 0.15 0.16 0.17 0.17 0.17 0.16 0.15 0.13 0.11 0.08]]
def bivariate_normal(X, Y, sigmax=1.0, sigmay=1.0,
mux=0.0, muy=0.0, sigmaxy=0.0):
"""
Bivariate gaussan distribution for equal shape X, Y
http://mathworld.wolfram.com/BivariateNormalDistribution.html
"""
Xmu = X-mux
Ymu = Y-muy
rho = sigmaxy/(sigmax*sigmay)
z = Xmu**2/sigmax**2 + Ymu**2/sigmay - 2*rho*Xmu*Ymu/(sigmax*sigmay)
return 1.0/(2*pi*sigmax*sigmay*(1-rho**2)) * exp( -z/(2*(1-rho**2)))
-------------------------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-users
