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"""
Ccorana's function
References::
[1] Storn, R. and Price, K. Differential Evolution - A Simple and Efficient
Heuristic for Global Optimization over Continuous Spaces. Journal of Global
Optimization 11: 341-359, 1997.
[2] Storn, R. and Price, K.
(Same title as above, but as a technical report.)
http://www.icsi.berkeley.edu/~storn/deshort1.ps
"""
from math import pow
from numpy import sign, floor, inf
def corana(coeffs):
"""
evaluates the Corana function for a list of coeffs
minimum is f(x)=0.0 at xi=0.0
"""
d = [1., 1000., 10., 100.]
x = coeffs
r = 0
for xj,dj in zip(x,d):
zj = floor( abs(xj/0.2) + 0.49999 ) * sign(xj) * 0.2
if abs(xj-zj) < 0.05:
r += 0.15 * pow(zj - 0.05*sign(zj), 2) * dj
else:
r += dj * xj ** 2
return r
def corana1d(x):
"""Corana in 1D; coeffs = (x,0,0,0)"""
return corana([x[0], 0, 0, 0])
def corana2d(x):
"""Corana in 2D; coeffs = (x,0,y,0)"""
return corana([x[0], 0, x[1], 0])
def corana3d(x):
"""Corana in 3D; coeffs = (x,0,y,z)"""
return corana([x[0], 0, x[1], x[2]])
Po = [1,1,1,1]
Plo = [-inf,-inf,-inf,-inf]
Phi = [inf,inf,inf,inf]
def s(V,*args):
retval = []
for i in args: retval.append(V[i])
return retval
from .model import Function
corana1d = Function(f=corana1d, limits=(s(Plo,0),s(Phi,0)),
start=s(Po,0))
corana2d = Function(f=corana2d, limits=(s(Plo,0,2),s(Phi,0,2)),
start=s(Po,0,2))
corana3d = Function(f=corana3d, limits=(s(Plo,0,2,3),s(Phi,0,2,3)),
start=s(Po,0,2,3))
corana4d = Function(f=corana, limits=(Plo,Phi), start=Po)
# End of file
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