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fitCurve.py
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fitCurve.py
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import string
import numpy
def fitPolynomial(data2D,degree):
a, b = [], []
j=0
for k in range(0,len(data2D)):
data=data2D[k]
ln=[0.0]*(degree+1)
if(isinstance(data,list)):
for i in range(0,degree+1):
ln[i] = float(pow(data[0],i))
else:
for i in range(0,degree+1):
ln[i] = float(pow(k,i))
y = 0.0
if(isinstance(data,list)):
y = float(data[1])
else:
y=float(data)
if(j!=0):
a[j].append(ln)
b[j].append(float(y))
else:
a.append(ln)
b.append(float(y))
A, B = numpy.matrix(a), numpy.matrix(b).transpose()
coeff= ((A.transpose() * A).getI()) * A.transpose() * B
return numpy.asarray(coeff)
def fitParabola(data2D):
s11, s12, s22, sy1, sy2, s1, s2, sy = 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
N=len(data2D)
for i in range(0,N):
data = data2D[i]
x, y = 0.0, 0.0
if(isinstance(data,list)):
x, y = data[0], data[1]
else:
x = i
y= data
x1, x2 = x, x**2
s11 += x1**2
s12 += x1*x2
s22 += x2**2
sy1 += y*x1
sy2 += y*x2
s1 += x1
s2 += x2
sy += y
s11 -= s1**2/N
s12 -= s1*s2/N
s22 -= s2**2/N
sy1 -= sy*s1/N
sy2 -= sy*s2/N
out2 = (sy1*s22-sy2*s12)/(s22*s11-s12**2)
out3 = (sy2*s11 - sy1* s12)/(s22*s11 - s12**2)
out1 = sy/N - out2*s1/N - out3*s2/N
return [out1,out2, out3]