id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
4879	Apparent bugs in ibeta_inv_imp (math::specialfunctions)	charles.southey@…	John Maddock	"Hi,

There seem to be a couple of bugs in the above function (which is in boost\math\special_functions\detail\ibeta_inverse.hpp):

The first is the condition:

'''if((lambda >= 0.2) && (lambda <= 0.8) && (lambda >= 10))'''

This clearly can never evaluate to true (lambda <= 0.8 AND >= 10) - so the following code block can never be executed. I'm guessing that the third lambda should be replaced with '''r''' (a parameter defined a couple of lines higher which could reasonably satisfy the condition) - but I'm not a mathematician and so this is just a guess.

The second apparent problem is an inconsistency in the handling of the boolean flag '''invert'''. Initially set to ''false'', in some parts of the code it is toggled to its complement whenever parameters '''a''' and '''b''' are swapped (which can happen more than once). However in other parts of the code it is simply set to ''true''. Again I'm afraid I don't know enough to be sure that the latter is wrong, but changing all instances where it is set to ''true'' to instead set it to its complement fixes a problem I was getting with the Fisher_F distribution which relies on this function.

Could someone with more understanding than me of what's going here have a look at these ?
"	Bugs	closed	To Be Determined	math	Boost 1.44.0	Problem	fixed