|   | 1 |  initial version  | 
Interestingly,
sage: integrate(abs(sin(x)),x)
-(2*arctan(sin(x)/(cos(x) + 1))*sin(x)/(cos(x) + 1) - log(2))*sgn(1/(cos(x) + 1))*sgn(sin(x)) - log(2*sin(x)^2/(cos(x) + 1)^2 + 2)*sgn(1/(cos(x) + 1))*sgn(sin(x)) + log(sin(x)^2/(cos(x) + 1)^2 + 1)*sgn(1/(cos(x) + 1))*sgn(sin(x)) + 2*(sin(x)/((sin(x)^2/(cos(x) + 1)^2 + 1)*(cos(x) + 1)) + arctan(sin(x)/(cos(x) + 1)))*abs(sin(x))/abs(cos(x) + 1)
Not that this is all that useful, because if we call this f then f(pi) has division by zero error, and based on comments elsewhere it is probably wrong in any case.  I have to admit I am surprised this isn't doable, though.   See this ticket 17511 but there are lots of places this question has recurred.
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                Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.