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<old>what is the way to convert a integer that has a zero fractional part to a true integer that can be used with vector-ref for example?

<old>e.g.: (vector-ref histogram (/ 0.5 0.1)) <=> (vector-ref histogram 5.0)

<old>The 5.0 is problematic here. How can I make it to only 5

<haugh>old, inexact->exact

<old>(inexact->exact) would work for this case, but in other case it would give a fraction

<old>(/ 0.6 0.1)

<old>-> 6755399441055743/1125899906842624

<old>is there a way to just extract the non-fractional part of a number?

<old>floor does not work also

<old>(floor 6.0) => 6.0

<haugh>(compose inexact->exact floor)

<old>floor seems to make 6.0 to 5

<old>but ceiling would do for that

<old>thanks!

<rlb>old: depending on what you want perhaps (inexact->exact (round x)) would suffice.

<old>rlb: I'm quite confuse by why it works

<old>(inexact->exact (round (/ 0.6 0.1))) => 6

<old>(round (/ 0.6 0.1)) => 6.0

<old>(inexact->exact (/ 0.6 0.1)) => 6755399441055743/1125899906842624

<old>Is this a REPL thing

<mirai>I'd do (inexact->exact (round-quotient 0.6 0.1))

<mirai>old: that 6.0 you got after round (or if you were to type in) would be represented as 0x40C00000 (binary32)

<mirai>which does round to the integer 6

<mirai>that division also gives the same result in binary32

<mirai>however… things aren't so with binary64

<mirai>6.0 => 0x4018000000000000 ; (/ 0.6 0.1) = 5.999999999999999 => 0x4017FFFFFFFFFFFF

<mirai>I don't know what precision Guile does its stuff in

<mirai>but your results seem to be related to precision

<mirai>btw inexact->exact doesn't mean that you get an integer

<mirai>you get a rational

<old>mirai: I see. weird thing can happen hm

<old>something something floating point yet again

<old>And right. Integer are rational so that make sens to get a huge fraction if the result is not round properly

<haugh>old, not sure about your larger application but you can start with rationals to avoid float quirks

<haugh>(/ 6/10 1/10)

<haugh>I avoid floats at all costs

<old>hmm that's not a bad idea at all

<old>I only have to change a single constant in my code : 0.1 => 1/10

<old>and it fixes the issue

<old>thanks!

<haugh>Can I return the module from which I obtained a given binding?

2023-08-30.log