(%i1) radcan(sqrt((5c/6-250/183)^2+(100/61-c)^2));
(%o1) (61c-100)/(6*sqrt(61))
The result could be negative, but it is a sqrt(...).
(%i2) factor(sqrt((5c/6-250/183)^2+(100/61-c)^2));
(%o2) abs(61c-100)/(6*sqrt(61))
Here we get the required abs(x) function.
The error appears regardless of the setting of radexpand
Rupert Swarbrick
2014-02-19
This is actually the expected behaviour of radcan. Unfortunately, its documentation isn't all that brilliant at the moment - I think Raymond Toy has been trying to come up with a more formal specification. He explains what's going on in a similar bug report here: https://sourceforge.net/p/maxima/bugs/2479/
In this case, the point is that if c is large then 61 * c >> 100.
Rupert Swarbrick
2014-02-19