Am 04.05.2014 17:27, schrieb Eric MSP Veith:

On Saturday 03 May 2014 10:26:58, [email protected] wrote:

x / 23.0 - (x / 23) evaluates to zero, assuming x is a Float.

(Which seems to be implied since you talk about the slope.)

Not quite, since x/23 is an integer division, as Kevin pointed out.

It’s the same as x / 23.0 - floor(x / 23.0). Leaving arithmetic

underflows [1] aside, it will be 0 iff x = i*23 (i = 1, 2, …,

n).

Not quite, when you assume x to be a Float - as clearly stated

in my post - then x/23 is *not* an integer division.

Still, finding the slope of f(x) at x means calculating f’(x),

i.e., derive f(x). Which has nothing to do with Ruby, but is a math

question.

On the other hand, when you assume x to be an Integer then f’(x) would

not be mathematically defined…

Probably the OP simply meant f(n+1) - f(n).

Regards,

Marcus