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""" Symbolic Integration """
#***************************************************************************** # Copyright (C) 2009 Golam Mortuza Hossain <gmhossain@gmail.com> # Copyright (C) 2010 Burcin Erocal <burcin@erocal.org> # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 2 of the License, or # (at your option) any later version. # http://www.gnu.org/licenses/ #*****************************************************************************` from __future__ import print_function
from sage.symbolic.ring import SR, is_SymbolicVariable from sage.symbolic.function import BuiltinFunction, Function
################################################################## # Table of available integration routines ##################################################################
# Add new integration routines to the dictionary below. This will make them # accessible with the 'algorithm' keyword parameter of top level integrate(). available_integrators = {}
import sage.symbolic.integration.external as external available_integrators['maxima'] = external.maxima_integrator available_integrators['sympy'] = external.sympy_integrator available_integrators['mathematica_free'] = external.mma_free_integrator available_integrators['fricas'] = external.fricas_integrator available_integrators['giac'] = external.giac_integrator
###################################################### # # Class implementing symbolic integration # ######################################################
class IndefiniteIntegral(BuiltinFunction): def __init__(self): """ Class to represent an indefinite integral.
EXAMPLES::
sage: from sage.symbolic.integration.integral import indefinite_integral sage: indefinite_integral(log(x), x) #indirect doctest x*log(x) - x sage: indefinite_integral(x^2, x) 1/3*x^3 sage: indefinite_integral(4*x*log(x), x) 2*x^2*log(x) - x^2 sage: indefinite_integral(exp(x), 2*x) 2*e^x
""" # The automatic evaluation routine will try these integrators # in the given order. This is an attribute of the class instead of # a global variable in this module to enable customization by # creating a subclasses which define a different set of integrators self.integrators = [external.maxima_integrator]
BuiltinFunction.__init__(self, "integrate", nargs=2, conversions={'sympy': 'Integral', 'giac': 'integrate'})
def _eval_(self, f, x): """ EXAMPLES::
sage: from sage.symbolic.integration.integral import indefinite_integral sage: indefinite_integral(exp(x), x) # indirect doctest e^x sage: indefinite_integral(exp(x), x^2) 2*(x - 1)*e^x """ # Check for x else: return None
# we try all listed integration algorithms except NotImplementedError: pass return None
def _tderivative_(self, f, x, diff_param=None): """ EXAMPLES::
sage: from sage.symbolic.integration.integral import indefinite_integral sage: f = function('f'); a,b=var('a,b') sage: h = indefinite_integral(f(x), x) sage: h.diff(x) # indirect doctest f(x) sage: h.diff(a) 0 """ else:
def _print_latex_(self, f, x): """ EXAMPLES::
sage: from sage.symbolic.integration.integral import indefinite_integral sage: print_latex = indefinite_integral._print_latex_ sage: var('x,a,b') (x, a, b) sage: f = function('f') sage: print_latex(f(x),x) '\\int f\\left(x\\right)\\,{d x}' sage: latex(integrate(tan(x)/x, x)) \int \frac{\tan\left(x\right)}{x}\,{d x} """ dx_str = "{d \\left(%s\\right)}"%(latex(x)) else:
indefinite_integral = IndefiniteIntegral()
class DefiniteIntegral(BuiltinFunction): def __init__(self): """ The symbolic function representing a definite integral.
EXAMPLES::
sage: from sage.symbolic.integration.integral import definite_integral sage: definite_integral(sin(x),x,0,pi) 2 """ # The automatic evaluation routine will try these integrators # in the given order. This is an attribute of the class instead of # a global variable in this module to enable customization by # creating a subclasses which define a different set of integrators self.integrators = [external.maxima_integrator]
BuiltinFunction.__init__(self, "integrate", nargs=4, conversions={'sympy': 'Integral', 'giac': 'integrate'})
def _eval_(self, f, x, a, b): """ Return the results of symbolic evaluation of the integral
EXAMPLES::
sage: from sage.symbolic.integration.integral import definite_integral sage: definite_integral(exp(x),x,0,1) # indirect doctest e - 1 """ # Check for x if len(x.variables()) == 1: nx = x.variables()[0] f = f*x.diff(nx) x = nx else: return None
# we try all listed integration algorithms pass return None
def _evalf_(self, f, x, a, b, parent=None, algorithm=None): """ Return a numerical approximation of the integral
EXAMPLES::
sage: from sage.symbolic.integration.integral import definite_integral sage: h = definite_integral(sin(x)*log(x)/x^2, x, 1, 2); h integrate(log(x)*sin(x)/x^2, x, 1, 2) sage: h.n() # indirect doctest 0.14839875208053...
TESTS:
Check if :trac:`3863` is fixed::
sage: integrate(x^2.7 * e^(-2.4*x), x, 0, 3).n() 0.154572952320790 """ # The gsl routine returns a tuple, which also contains the error. # We only return the result.
def _tderivative_(self, f, x, a, b, diff_param=None): """ Return the derivative of symbolic integration
EXAMPLES::
sage: from sage.symbolic.integration.integral import definite_integral sage: f = function('f'); a,b=var('a,b') sage: h = definite_integral(f(x), x,a,b) sage: h.diff(x) # indirect doctest 0 sage: h.diff(a) -f(a) sage: h.diff(b) f(b) """ # integration variable != differentiation variable else: - f.subs(x==a)*a.diff(diff_param)
def _print_latex_(self, f, x, a, b): r""" Convert this integral to LaTeX notation
EXAMPLES::
sage: from sage.symbolic.integration.integral import definite_integral sage: print_latex = definite_integral._print_latex_ sage: var('x,a,b') (x, a, b) sage: f = function('f') sage: print_latex(f(x),x,0,1) '\\int_{0}^{1} f\\left(x\\right)\\,{d x}' sage: latex(integrate(tan(x)/x, x, 0, 1)) \int_{0}^{1} \frac{\tan\left(x\right)}{x}\,{d x} """ dx_str = "{d \\left(%s\\right)}"%(latex(x)) else:
def _sympy_(self, f, x, a, b): """ Convert this integral to the equivalent SymPy object
The resulting SymPy integral can be evaluated using ``doit()``.
EXAMPLES::
sage: integral(x, x, 0, 1, hold=True)._sympy_() Integral(x, (x, 0, 1)) sage: _.doit() 1/2 """
definite_integral = DefiniteIntegral()
def _normalize_integral_input(f, v=None, a=None, b=None): r""" Validate and return variable and endpoints for an integral.
INPUT:
- ``f`` -- an expression to integrate;
- ``v`` -- a variable of integration or a triple;
- ``a`` -- (optional) the left endpoint of integration;
- ``b`` -- (optional) the right endpoint of integration.
It is also possible to pass last three parameters in ``v`` as a triple.
OUTPUT:
- a tuple of ``f``, ``v``, ``a``, and ``b``.
EXAMPLES::
sage: from sage.symbolic.integration.integral import \ ....: _normalize_integral_input sage: _normalize_integral_input(x^2, x, 0, 3) (x^2, x, 0, 3) sage: _normalize_integral_input(x^2, [x, 0, 3], None, None) (x^2, x, 0, 3) sage: _normalize_integral_input(x^2, [0, 3], None, None) doctest:...: DeprecationWarning: Variable of integration should be specified explicitly. See http://trac.sagemath.org/12438 for details. (x^2, x, 0, 3) sage: _normalize_integral_input(x^2, [x], None, None) (x^2, x, None, None) """ else: "with or without two endpoints" % repr(v)) # two arguments, must be endpoints v, a, b = None, v, a f = f(v) raise TypeError('only one endpoint was given!')
def integrate(expression, v=None, a=None, b=None, algorithm=None, hold=False): r""" Returns the indefinite integral with respect to the variable `v`, ignoring the constant of integration. Or, if endpoints `a` and `b` are specified, returns the definite integral over the interval `[a, b]`.
If ``self`` has only one variable, then it returns the integral with respect to that variable.
If definite integration fails, it could be still possible to evaluate the definite integral using indefinite integration with the Newton - Leibniz theorem (however, the user has to ensure that the indefinite integral is continuous on the compact interval `[a,b]` and this theorem can be applied).
INPUT:
- ``v`` - a variable or variable name. This can also be a tuple of the variable (optional) and endpoints (i.e., ``(x,0,1)`` or ``(0,1)``).
- ``a`` - (optional) lower endpoint of definite integral
- ``b`` - (optional) upper endpoint of definite integral
- ``algorithm`` - (default: 'maxima') one of
- 'maxima' - use maxima (the default)
- 'sympy' - use sympy (also in Sage)
- 'mathematica_free' - use http://integrals.wolfram.com/
- 'fricas' - use FriCAS (the optional fricas spkg has to be installed)
- 'giac' - use Giac
To prevent automatic evaluation use the ``hold`` argument.
.. SEEALSO::
To integrate a polynomial over a polytope, use the optional ``latte_int`` package :meth:`sage.geometry.polyhedron.base.Polyhedron_base.integrate`.
EXAMPLES::
sage: x = var('x') sage: h = sin(x)/(cos(x))^2 sage: h.integral(x) 1/cos(x)
::
sage: f = x^2/(x+1)^3 sage: f.integral(x) 1/2*(4*x + 3)/(x^2 + 2*x + 1) + log(x + 1)
::
sage: f = x*cos(x^2) sage: f.integral(x, 0, sqrt(pi)) 0 sage: f.integral(x, a=-pi, b=pi) 0
::
sage: f(x) = sin(x) sage: f.integral(x, 0, pi/2) 1
The variable is required, but the endpoints are optional::
sage: y=var('y') sage: integral(sin(x), x) -cos(x) sage: integral(sin(x), y) y*sin(x) sage: integral(sin(x), x, pi, 2*pi) -2 sage: integral(sin(x), y, pi, 2*pi) pi*sin(x) sage: integral(sin(x), (x, pi, 2*pi)) -2 sage: integral(sin(x), (y, pi, 2*pi)) pi*sin(x)
Using the ``hold`` parameter it is possible to prevent automatic evaluation, which can then be evaluated via :meth:`simplify`::
sage: integral(x^2, x, 0, 3) 9 sage: a = integral(x^2, x, 0, 3, hold=True) ; a integrate(x^2, x, 0, 3) sage: a.simplify() 9
Constraints are sometimes needed::
sage: var('x, n') (x, n) sage: integral(x^n,x) Traceback (most recent call last): ... ValueError: Computation failed since Maxima requested additional constraints; using the 'assume' command before evaluation *may* help (example of legal syntax is 'assume(n>0)', see `assume?` for more details) Is n equal to -1? sage: assume(n > 0) sage: integral(x^n,x) x^(n + 1)/(n + 1) sage: forget()
Usually the constraints are of sign, but others are possible::
sage: assume(n==-1) sage: integral(x^n,x) log(x)
Note that an exception is raised when a definite integral is divergent::
sage: forget() # always remember to forget assumptions you no longer need sage: integrate(1/x^3,(x,0,1)) Traceback (most recent call last): ... ValueError: Integral is divergent. sage: integrate(1/x^3,x,-1,3) Traceback (most recent call last): ... ValueError: Integral is divergent.
But Sage can calculate the convergent improper integral of this function::
sage: integrate(1/x^3,x,1,infinity) 1/2
The examples in the Maxima documentation::
sage: var('x, y, z, b') (x, y, z, b) sage: integral(sin(x)^3, x) 1/3*cos(x)^3 - cos(x) sage: integral(x/sqrt(b^2-x^2), b) x*log(2*b + 2*sqrt(b^2 - x^2)) sage: integral(x/sqrt(b^2-x^2), x) -sqrt(b^2 - x^2) sage: integral(cos(x)^2 * exp(x), x, 0, pi) 3/5*e^pi - 3/5 sage: integral(x^2 * exp(-x^2), x, -oo, oo) 1/2*sqrt(pi)
We integrate the same function in both Mathematica and Sage (via Maxima)::
sage: _ = var('x, y, z') sage: f = sin(x^2) + y^z sage: g = mathematica(f) # optional - mathematica sage: print(g) # optional - mathematica z 2 y + Sin[x ] sage: print(g.Integrate(x)) # optional - mathematica z Pi 2 x y + Sqrt[--] FresnelS[Sqrt[--] x] 2 Pi sage: print(f.integral(x)) x*y^z + 1/16*sqrt(pi)*((I + 1)*sqrt(2)*erf((1/2*I + 1/2)*sqrt(2)*x) + (I - 1)*sqrt(2)*erf((1/2*I - 1/2)*sqrt(2)*x) - (I - 1)*sqrt(2)*erf(sqrt(-I)*x) + (I + 1)*sqrt(2)*erf((-1)^(1/4)*x))
Alternatively, just use algorithm='mathematica_free' to integrate via Mathematica over the internet (does NOT require a Mathematica license!)::
sage: _ = var('x, y, z') # optional - internet sage: f = sin(x^2) + y^z # optional - internet sage: f.integrate(x, algorithm="mathematica_free") # optional - internet x*y^z + sqrt(1/2)*sqrt(pi)*fresnels(sqrt(2)*x/sqrt(pi))
We can also use Sympy::
sage: integrate(x*sin(log(x)), x) -1/5*x^2*(cos(log(x)) - 2*sin(log(x))) sage: integrate(x*sin(log(x)), x, algorithm='sympy') -1/5*x^2*cos(log(x)) + 2/5*x^2*sin(log(x)) sage: _ = var('y, z') sage: (x^y - z).integrate(y) -y*z + x^y/log(x) sage: (x^y - z).integrate(y, algorithm="sympy") -y*z + cases(((log(x) == 0, y), (1, x^y/log(x))))
We integrate the above function in Maple now::
sage: g = maple(f); g.sort() # optional - maple y^z+sin(x^2) sage: g.integrate(x).sort() # optional - maple x*y^z+1/2*2^(1/2)*Pi^(1/2)*FresnelS(2^(1/2)/Pi^(1/2)*x)
We next integrate a function with no closed form integral. Notice that the answer comes back as an expression that contains an integral itself.
::
sage: A = integral(1/ ((x-4) * (x^3+2*x+1)), x); A -1/73*integrate((x^2 + 4*x + 18)/(x^3 + 2*x + 1), x) + 1/73*log(x - 4)
We now show that floats are not converted to rationals automatically since we by default have keepfloat: true in maxima.
::
sage: integral(e^(-x^2),(x, 0, 0.1)) 0.05623145800914245*sqrt(pi)
An example of an integral that fricas can integrate, but the default integrator cannot::
sage: f(x) = sqrt(x+sqrt(1+x^2))/x sage: integrate(f(x), x, algorithm="fricas") # optional - fricas 2*sqrt(x + sqrt(x^2 + 1)) - 2*arctan(sqrt(x + sqrt(x^2 + 1))) - log(sqrt(x + sqrt(x^2 + 1)) + 1) + log(sqrt(x + sqrt(x^2 + 1)) - 1)
The following definite integral is not found with the default integrator::
sage: f(x) = (x^4 - 3*x^2 + 6) / (x^6 - 5*x^4 + 5*x^2 + 4) sage: integrate(f(x), x, 1, 2) integrate((x^4 - 3*x^2 + 6)/(x^6 - 5*x^4 + 5*x^2 + 4), x, 1, 2)
Both fricas and sympy give the correct result::
sage: integrate(f(x), x, 1, 2, algorithm="fricas") # optional - fricas -1/2*pi + arctan(8) + arctan(5) + arctan(2) + arctan(1/2) sage: integrate(f(x), x, 1, 2, algorithm="sympy") -1/2*pi + arctan(8) + arctan(5) + arctan(2) + arctan(1/2)
Using Giac to integrate the absolute value of a trigonometric expression::
sage: integrate(abs(cos(x)), x, 0, 2*pi, algorithm='giac') 4
ALIASES: integral() and integrate() are the same.
EXAMPLES:
Here is an example where we have to use assume::
sage: a,b = var('a,b') sage: integrate(1/(x^3 *(a+b*x)^(1/3)), x) Traceback (most recent call last): ... ValueError: Computation failed since Maxima requested additional constraints; using the 'assume' command before evaluation *may* help (example of legal syntax is 'assume(a>0)', see `assume?` for more details) Is a positive or negative?
So we just assume that `a>0` and the integral works::
sage: assume(a>0) sage: integrate(1/(x^3 *(a+b*x)^(1/3)), x) 2/9*sqrt(3)*b^2*arctan(1/3*sqrt(3)*(2*(b*x + a)^(1/3) + a^(1/3))/a^(1/3))/a^(7/3) - 1/9*b^2*log((b*x + a)^(2/3) + (b*x + a)^(1/3)*a^(1/3) + a^(2/3))/a^(7/3) + 2/9*b^2*log((b*x + a)^(1/3) - a^(1/3))/a^(7/3) + 1/6*(4*(b*x + a)^(5/3)*b^2 - 7*(b*x + a)^(2/3)*a*b^2)/((b*x + a)^2*a^2 - 2*(b*x + a)*a^3 + a^4)
TESTS:
The following integral was broken prior to Maxima 5.15.0 - see :trac:`3013`::
sage: integrate(sin(x)*cos(10*x)*log(x), x) -1/198*(9*cos(11*x) - 11*cos(9*x))*log(x) + 1/44*Ei(11*I*x) - 1/36*Ei(9*I*x) - 1/36*Ei(-9*I*x) + 1/44*Ei(-11*I*x)
It is no longer possible to use certain functions without an explicit variable. Instead, evaluate the function at a variable, and then take the integral::
sage: integrate(sin) Traceback (most recent call last): ... TypeError: unable to convert sin to a symbolic expression
sage: integrate(sin(x), x) -cos(x) sage: integrate(sin(x), x, 0, 1) -cos(1) + 1
Check if :trac:`780` is fixed::
sage: _ = var('x,y') sage: f = log(x^2+y^2) sage: res = integral(f,x,0.0001414, 1.); res Traceback (most recent call last): ... ValueError: Computation failed since Maxima requested additional constraints; using the 'assume' command before evaluation *may* help (example of legal syntax is 'assume(50015104*y^2-50015103>0)', see `assume?` for more details) Is 50015104*y^2-50015103 positive, negative or zero? sage: assume(y>1) sage: res = integral(f,x,0.0001414, 1.); res 2*y*arctan(1.0/y) - 2*y*arctan(0.0001414/y) + 1.0*log(1.0*y^2 + 1.0) - 0.0001414*log(1.0*y^2 + 1.9993959999999997e-08) - 1.9997172 sage: nres = numerical_integral(f.subs(y=2), 0.0001414, 1.); nres (1.4638323264144..., 1.6251803529759...e-14) sage: res.subs(y=2).n() 1.46383232641443 sage: nres = numerical_integral(f.subs(y=.5), 0.0001414, 1.); nres (-0.669511708872807, 7.768678110854711e-15) sage: res.subs(y=.5).n() -0.669511708872807
Check if :trac:`6816` is fixed::
sage: var('t,theta') (t, theta) sage: integrate(t*cos(-theta*t),t,0,pi) (pi*theta*sin(pi*theta) + cos(pi*theta))/theta^2 - 1/theta^2 sage: integrate(t*cos(-theta*t),(t,0,pi)) (pi*theta*sin(pi*theta) + cos(pi*theta))/theta^2 - 1/theta^2 sage: integrate(t*cos(-theta*t),t) (t*theta*sin(t*theta) + cos(t*theta))/theta^2 sage: integrate(x^2,(x)) # this worked before 1/3*x^3 sage: integrate(x^2,(x,)) # this didn't 1/3*x^3 sage: integrate(x^2,(x,1,2)) 7/3 sage: integrate(x^2,(x,1,2,3)) Traceback (most recent call last): ... ValueError: invalid input (x, 1, 2, 3) - please use variable, with or without two endpoints
Note that this used to be the test, but it is actually divergent (Maxima currently asks for assumptions on theta)::
sage: integrate(t*cos(-theta*t),(t,-oo,oo)) Traceback (most recent call last): ... ValueError: Computation failed since Maxima requested additional constraints;...
Check if :trac:`6189` is fixed::
sage: n = N; n <function numerical_approx at ...> sage: F(x) = 1/sqrt(2*pi*1^2)*exp(-1/(2*1^2)*(x-0)^2) sage: G(x) = 1/sqrt(2*pi*n(1)^2)*exp(-1/(2*n(1)^2)*(x-n(0))^2) sage: integrate( (F(x)-F(x))^2, x, -infinity, infinity).n() 0.000000000000000 sage: integrate( ((F(x)-G(x))^2).expand(), x, -infinity, infinity).n() -6.26376265908397e-17 sage: integrate( (F(x)-G(x))^2, x, -infinity, infinity).n()# abstol 1e-6 0
This was broken before Maxima 5.20::
sage: exp(-x*i).integral(x,0,1) I*e^(-I) - I
Test deprecation warning when variable is not specified::
sage: x.integral() doctest:...: DeprecationWarning: Variable of integration should be specified explicitly. See http://trac.sagemath.org/12438 for details. 1/2*x^2
Test that :trac:`8729` is fixed::
sage: t = var('t') sage: a = sqrt((sin(t))^2 + (cos(t))^2) sage: integrate(a, t, 0, 2*pi) 2*pi sage: a.simplify_full().simplify_trig() 1
Maxima uses Cauchy Principal Value calculations to integrate certain convergent integrals. Here we test that this does not raise an error message (see :trac:`11987`)::
sage: integrate(sin(x)*sin(x/3)/x^2, x, 0, oo) 1/6*pi
Maxima returned a negative value for this integral prior to maxima-5.24 (:trac:`10923`). Ideally we would get an answer in terms of the gamma function; however, we get something equivalent::
sage: actual_result = integral(e^(-1/x^2), x, 0, 1) sage: actual_result.canonicalize_radical() (sqrt(pi)*(erf(1)*e - e) + 1)*e^(-1) sage: ideal_result = 1/2*gamma(-1/2, 1) sage: error = actual_result - ideal_result sage: error.numerical_approx() # abs tol 1e-10 0
We will not get an evaluated answer here, which is better than the previous (wrong) answer of zero. See :trac:`10914`::
sage: f = abs(sin(x)) sage: integrate(f, x, 0, 2*pi) # long time (4s on sage.math, 2012) integrate(abs(sin(x)), x, 0, 2*pi)
Another incorrect integral fixed upstream in Maxima, from :trac:`11233`::
sage: a,t = var('a,t') sage: assume(a>0) sage: assume(x>0) sage: f = log(1 + a/(x * t)^2) sage: F = integrate(f, t, 1, Infinity) sage: F(x=1, a=7).numerical_approx() # abs tol 1e-10 4.32025625668262 sage: forget()
Verify that MinusInfinity works with sympy (:trac:`12345`)::
sage: integral(1/x^2, x, -infinity, -1, algorithm='sympy') 1
Check that :trac:`11737` is fixed::
sage: N(integrate(sin(x^2)/(x^2), x, 1, infinity), prec=54) 0.285736646322853 sage: N(integrate(sin(x^2)/(x^2), x, 1, infinity)) # known bug (non-zero imag part) 0.285736646322853
Check that :trac:`14209` is fixed::
sage: integral(e^(-abs(x))/cosh(x),x,-infinity,infinity) 2*log(2) sage: integral(e^(-abs(x))/cosh(x),x,-infinity,infinity) 2*log(2)
Check that :trac:`12628` is fixed::
sage: var('z,n') (z, n) sage: f(z, n) = sin(n*z) / (n*z) sage: integrate(f(z,1)*f(z,3)*f(z,5)*f(z,7),z,0,oo) 22/315*pi sage: for k in srange(1, 16, 2): ....: print(integrate(prod(f(z, ell) ....: for ell in srange(1, k+1, 2)), z, 0, oo)) 1/2*pi 1/6*pi 1/10*pi 22/315*pi 3677/72576*pi 48481/1247400*pi 193359161/6227020800*pi 5799919/227026800*pi
Check that :trac:`12628` is fixed::
sage: integrate(1/(sqrt(x)*((1+sqrt(x))^2)),x,1,9) 1/2
Check that :trac:`8728` is fixed::
sage: forget() sage: c,w,T = var('c,w,T') sage: assume(1-c^2 > 0) sage: assume(abs(c) - sqrt(1-c^2) - 1 > 0) sage: assume(abs(sqrt(1-c^2)-1) - abs(c) > 0) sage: integrate(cos(w+T) / (1+c*cos(T))^2, T, 0, 2*pi) 2*pi*sqrt(-c^2 + 1)*c*cos(w)/(c^4 - 2*c^2 + 1)
Check that :trac:`13733` is fixed::
sage: a = integral(log(cot(x) - 1), x, 0, pi/4); a # long time (about 6 s) -1/4*pi*log(2) - 1/2*I*dilog(I + 1) + 1/2*I*dilog(-I + 1) + 1/2*I*dilog(1/2*I + 1/2) - 1/2*I*dilog(-1/2*I + 1/2) sage: abs(N(a - pi*log(2)/8)) < 1e-15 # long time True
Check that :trac:`17968` is fixed::
sage: a = N(integrate(exp(x^3), (x, 1, 2)), prec=54) sage: a.real_part() # abs tol 1e-13 275.510983763312 sage: a.imag_part() # abs tol 1e-13 0.0 """ raise ValueError("Unknown algorithm: %s" % algorithm) else:
integral = integrate |