Testing ellipse conversion

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# set up
import numpy as np
from numpy import linalg as LA
from math import atan2
import sys
import os
sys.path.insert(0, os.path.abspath('..'))

import salientregions as sr


    

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# elipse1
a = 15.9; b = 9.2; angle_rad = np.pi/8 #np.pi/13 #np.pi/4 #np.pi/3 #np.pi/2  #0- works only for angles in [0,90] deg.

[A, B, C] = sr.helpers.standard2poly_ellipse(a, b, angle_rad)

print "a, b, angle_rad:", a, b, angle_rad
print "A, B, C: ", A, B, C


    

    




  File "<ipython-input-2-e5a51ea71bc1>", line 6
    print "a, b, angle_rad:", a, b, angle_rad
                           ^
SyntaxError: Missing parentheses in call to 'print'

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# construct a matrix from the values 
M = np.array([[A,B],[B,C]])
print M


    

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# find the eigenvalues 
evals = LA.eigh(M)[0]
order = evals.argsort()[::-1]
evals = evals[order]
e_min = evals[-1]
e_max = evals[0]
print "Eigen values, min, max: ", evals, e_min, e_max


    

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#angle_rad_c = np.arctan2(*evecs[:, 0][::-1])
if B == 0:
    if A < C:
        angle_rad_c = 0
    else:
        angle_rad_c = np.pi/2
else:
    if A < C:
        angle_rad_c =  0.5*np.arctan(2*B/(A-C))    
    else:
        angle_rad_c = np.pi/2 + 0.5*np.arctan(2*B/(A-C))  
print "The angle (rad): ", angle_rad_c        
#if angle_rad_c < 0:
    #angle_rad_c = np.pi - angle_rad_c
#print "The angle (rad): ", angle_rad_c


    

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# axis lengths
a_c = 1/np.sqrt(e_min)
print "Major axis semi-length: ", a_c
b_c = 1/np.sqrt(e_max)
print "Minor axis semi-length: ", b_c


    

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print "difference true-converted angle: ", angle_rad - angle_rad_c
print "difference true-converted minor axis semi-len: ", b - b_c
print "difference true-converted major axis semi-len: ", a - a_c
assert sr.helpers.array_diff(angle_rad, angle_rad_c,1e-05, 1e-08)
assert sr.helpers.array_diff(a, a_c,1e-05, 1e-08)
assert sr.helpers.array_diff(b, b_c,1e-05, 1e-08)


    

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