Changeset 2015
 Timestamp:
 Nov 10, 2005, 1:22:03 PM (18 years ago)
 File:

 1 edited
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inundation/utilities/numerical_tools.py
r1910 r2015 3 3 4 4 """ 5 6 import Numeric 7 8 def mean(x): 9 """Mean value of a vector 10 """ 11 return(float(Numeric.sum(x))/len(x)) 12 13 14 def cov(x, y=None): 15 """Covariance of vectors x and y. 16 17 If y is None: return cov(x, x) 18 """ 19 20 if y is None: 21 y = x 22 23 assert(len(x)==len(y)) 24 N = len(x) 25 26 cx = x  mean(x) 27 cy = y  mean(y) 28 29 p = Numeric.innerproduct(cx,cy)/N 30 return(p) 31 32 33 def err(x, y=0, n=2): 34 """Relative error of xy to y 35 n = 2: Two norm 36 n = None: Max norm 37 38 If denominator evaluates to zero, absolute error is returned 39 """ 40 41 if n == 2: 42 err = norm(xy) 43 try: 44 err = err/norm(y) 45 except: 46 pass 47 48 else: 49 err = max(abs(xy)) 50 try: 51 err = err/max(abs(y)) 52 except: 53 pass 54 55 return err 56 57 58 def norm(x): 59 """2norm of x 60 """ 61 62 y = Numeric.ravel(x) 63 p = Numeric.sqrt(Numeric.innerproduct(y,y)) 64 return p 65 66 67 def corr(x, y=None): 68 """Correlation of x and y 69 If y is None return autocorrelation of x 70 """ 71 72 from math import sqrt 73 if y is None: 74 y = x 75 76 varx = cov(x) 77 vary = cov(y) 78 79 if varx == 0 or vary == 0: 80 C = 0 81 else: 82 C = cov(x,y)/sqrt(varx * vary) 83 84 return(C) 85 5 86 6 87 … … 34 115 return array(A).astype(typecode) 35 116 117 118
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