Forgot to attach file. Here it is #This is a file created by GMatH. ##! #I have also added this automatic import as a convenience. #Soon, you will be able to use a Druid to guide you through the import process! import sys from Numeric import zeros from RandomArray import random CON = 1.4 CON2 = CON*CON BIG = 1.0e30 SAFE = 2.0 MyError = "The choosen x is too small!" MyRealError = "The choosen x is not real!" def Diff(f, x): global CON, CON2, BIG, SAFE def func(g, t): return apply(g, (t,)) if type(x) == type(1.j): raise MyRealError, x if float(x) == 0.0: h = random()/1e-10 if float(x) != 0.0: h = float(x)/10 a = zeros((10,10),'d') if float(h) == 0.0: raise MyError, x try: test = func(f, x) test = func(f, x+h) test = func(f, x-h) except: print "Is function", str(f), "defined and continous around x =", x,"?" print sys.exc_type, sys.exc_value return None else : hh = h a[0][0] = (func(f, x + hh) - func(f, x - hh))/(2.0*hh) err = BIG ans = "CANNOT COMPUTE DERIVATIVE" for i in range(10): hh = hh/CON a[0,i] = (func(f, x + hh) - func(f, x - hh))/(2.0*hh) fac = CON2 for j in range(1, i+1): a[j][i]=(a[j-1][i]*fac - a[j-1][i-1])/(fac - 1.0) fac = CON2*fac errt = max(abs(a[j][i] - a[j-1][i]), abs(a[j][i] - a[j-1][i-1])) if errt <= err: err = errt ans = a[j][i] if abs(a[i][i] - a[i-1][i-1]) >= SAFE*err: return ans return ans def PDiff(f, var_index, *args): return 0