What am I Doing Wrong?

[Groover]

Hello, I am clearly making a stupid mistake, but what?

Arc length calculation:

x = Symbol('x')

 

formula = 2 * x**2

 

d = diff(formula, x)

i = integrate(sqrt(1 + d**2), (x, 5.0, 10.0))

gives a result of 150.087

but changing the formula to this:

formula = 0.26666 * x**2

gives a result of zero. In fact any coefficient less than one gives a result of zero.

Thanks, Andy

[Aaron Meurer]

Looks like you found a bug. I get the right result with meijerg=True,
which forces it to use that algorithm.

Aaron Meurer

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[Aaron Meurer]

I have opened https://github.com/sympy/sympy/issues/8685 for this, and
debugged the code a little bit and found the problem.

Aaron Meurer