Proper rounding implementation #23
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...in accordance with Basisregelwerk page 13 ("Rundungen").
The previous implementation relies on `string.format("%.0f", x)` whose
behaviour is inconsistent accross Lua versions.
- common.render_delta() used to generate the wrong sign for non-zero values in [-0.5, 0.5]. - Use local variable for sign character to better describe what's happening.
- Use a *local* variable to store intermediary results. - Emit "&" and the integral value with a single tex.sprint() since the latter can't result in special characters.
that previously involved `math.floor(x + 0.5)` or `string.format("%.0f", x)`.
flyx
requested changes
Mar 17, 2024
src/kampfbogen.lua
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| @@ -158,14 +159,14 @@ nahkampf_render[11]= {false, function(v, talent, ebe) | |||
| if talent == nil or #talent < 4 or atb == "" or #v < 8 then | |||
| return | |||
| end | |||
| tex.sprint(-2, atpa_mod(atb - common.round(ebe/2, true), talent.AT, v["TP/KK Schwelle"], v["TP/KK Schritt"], v["WM AT"], art(v), talent.Spezialisierungen)) | |||
| tex.sprint(-2, atpa_mod(atb - math.round(ebe/2, true), talent.AT, v["TP/KK Schwelle"], v["TP/KK Schritt"], v["WM AT"], art(v), talent.Spezialisierungen)) | |||
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math.round hat den zweiten Parameter nicht mehr, ist also an der Stelle falsch und müsste statt dessen math.floor sein.
Sonst wird bei einer ungeraden eBE ein Punkt zu viel von der AT abgezogen.
src/kampfbogen.lua
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| @@ -252,7 +253,7 @@ local waffenlos_render = { | |||
| added = added + 1 | |||
| end | |||
| end | |||
| tex.sprint(-2, atpa_mod(atb - common.round(ebe/2, true), talent.AT, v["TP/KK Schwelle"], v["TP/KK Schritt"], 0)) | |||
| tex.sprint(-2, atpa_mod(atb - math.round(ebe/2, true), talent.AT, v["TP/KK Schwelle"], v["TP/KK Schritt"], 0)) | |||
|
Danke für die Kommentare! Ich kümmere mich im Verlauf der Woche um die beiden Probleme. |
Strictly speaking, the rules of distribution of effective encumberance onto AT/PA values use integer floor/ceil division by two rather than rounding (Basisregelwerk, p. 137). So that's what we'll use in the implementation.
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…in accordance with Basisregelwerk page 13 (“Rundungen”).
The previous implementation relies on
string.format("%.0f", x)whose behaviour is inconsistent across Lua versions.Other rounding uses idioms like
math.floor(x + 0.5)which is fine for DSA number ranges but generally inexact,(n + d2) // d(wheredandd2are positive integer literals andd2is (d÷2) rounded down) which is a bit difficult to read and error-prone.Potential caveat: this implementation rounds halfway cases away from zero while the rules state that (barring special cases) they should be rounded “up”, i. e. towards positive infinity. However, I have yet to see a rule that requires the rounding of negative values (to any other value than zero); instances where negative modifiers need rounding (e. g. encumbrance), the rounding is supposed to be applied to their absolute values, i. e. away from zero.