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Calculating Integral

asked 2011-04-06 11:49:23 -0600

Sagud gravatar image

updated 2011-04-28 11:27:42 -0600

Kelvin Li gravatar image

f(x) = e**(-x) * log(x+1);
uu = integral(f, (x, 0, oo));
uu.n(digits=18)

why this dont work?

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answered 2011-04-06 14:59:19 -0600

benjaminfjones gravatar image

As far as I can tell, this seems to be a bug. uu evaluates to the expression e*expintegral_e(1, 1) and the expintegral_e function doesn't seem to be defined. There is a exponential_integral_1 function which seems to give the correct answer:

sage: N(e*exponential_integral_1(1), digits=18)
0.596347362323194107

This agrees with WolframAlpha.

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answered 2011-04-06 15:51:44 -0600

kcrisman gravatar image

Yup, @benjaminfjones is right on track.

sage: sage.symbolic.pynac.symbol_table['maxima']
{'elliptic_e': elliptic_e, 'imagpart': imag_part, 'acsch': arccsch, 'glaisher': glaisher, 'asinh': arcsinh,
'minf': -Infinity, 'elliptic_f': elliptic_f, '(1+sqrt(5))/2': golden_ratio, 'inf': +Infinity, 'log(2)': log2,
 'kron_delta': kronecker_delta, 'asin': arcsin, 'log': log, 'atanh': arctanh, 'brun': brun, '%pi': pi,    
'acosh': arccosh, 'sin': sin, 'mertens': mertens, 'ceiling': ceil, 'infinity': Infinity, 'elliptic_ec': 
elliptic_ec, 'atan': arctan, 'factorial': factorial, 'twinprime': twinprime, 'khinchin': khinchin, 
'catalan': catalan, 'signum': sgn, 'binomial': binomial, 'delta': dirac_delta, 'asec': arcsec, 
'elliptic_kc': elliptic_kc, '%gamma': euler_gamma, 'realpart': real_part, 'elliptic_eu': elliptic_eu, 
'cos': cos, 'acoth': arccoth, 'gamma_incomplete': gamma, 'li[2]': dilog, 'atan2': arctan2, 'exp': exp, 
'psi[0]': psi, 'asech': arcsech, 'acos': arccos, 'acot': arccot, 'acsc': arccsc, 'elliptic_pi': elliptic_pi}

We seem to be missing quite a few of the functions at The Maxima special function listing. Fixing this is Ticket #11143.

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Asked: 2011-04-06 11:49:23 -0600

Seen: 273 times

Last updated: Apr 06 '11