From 6dfef34a4bf2f3099b6744119e9c5488633e5c0e Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Fri, 24 Apr 2026 18:53:28 +0000
Subject: [PATCH] lua: math library
 (abs/trig/log/pow/min/max/fmod/modf/random/...) +17 tests

---
 lib/lua/runtime.sx | 113 +++++++++++++++++++++++++++++++++++++++++++++
 lib/lua/test.sh    |  55 ++++++++++++++++++++++
 plans/lua-on-sx.md |   3 +-
 3 files changed, 170 insertions(+), 1 deletion(-)

diff --git a/lib/lua/runtime.sx b/lib/lua/runtime.sx
index 2e99ebe6..dddbbfb4 100644
--- a/lib/lua/runtime.sx
+++ b/lib/lua/runtime.sx
@@ -878,3 +878,116 @@
 (dict-set! string "gmatch" lua-string-gmatch)
 (dict-set! string "gsub" lua-string-gsub)
 (dict-set! string "format" lua-string-format)
+
+;; ── math library ──────────────────────────────────────────────
+(define math {})
+
+(define lua-math-pi 3.141592653589793)
+(define lua-math-huge (/ 1.0 0.0))
+
+(define lua-math-abs (fn (x) (abs x)))
+(define lua-math-ceil (fn (x) (ceil x)))
+(define lua-math-floor (fn (x) (floor x)))
+(define lua-math-sqrt (fn (x) (sqrt x)))
+(define lua-math-exp (fn (x) (exp x)))
+(define lua-math-sin (fn (x) (sin x)))
+(define lua-math-cos (fn (x) (cos x)))
+(define lua-math-tan (fn (x) (tan x)))
+(define lua-math-asin (fn (x) (asin x)))
+(define lua-math-acos (fn (x) (acos x)))
+(define lua-math-atan (fn (x) (atan x)))
+(define lua-math-atan2 (fn (y x) (atan2 y x)))
+(define lua-math-pow (fn (a b) (pow a b)))
+
+(define lua-math-log
+  (fn (&rest args)
+    (cond
+      ((= (len args) 1) (log (first args)))
+      (else (/ (log (first args)) (log (nth args 1)))))))
+
+(define lua-math-log10
+  (fn (x) (/ (log x) (log 10))))
+
+(define lua-math-deg (fn (x) (* x (/ 180 lua-math-pi))))
+(define lua-math-rad (fn (x) (* x (/ lua-math-pi 180))))
+
+(define lua-math-min
+  (fn (&rest args)
+    (cond
+      ((= (len args) 0) (error "lua: min: no values"))
+      ((= (len args) 1) (first args))
+      (else
+        (let ((m (first args)))
+          (begin
+            (define
+              loop
+              (fn (i)
+                (when (< i (len args))
+                  (begin
+                    (when (< (nth args i) m) (set! m (nth args i)))
+                    (loop (+ i 1))))))
+            (loop 1)
+            m))))))
+
+(define lua-math-max
+  (fn (&rest args)
+    (cond
+      ((= (len args) 0) (error "lua: max: no values"))
+      ((= (len args) 1) (first args))
+      (else
+        (let ((m (first args)))
+          (begin
+            (define
+              loop
+              (fn (i)
+                (when (< i (len args))
+                  (begin
+                    (when (> (nth args i) m) (set! m (nth args i)))
+                    (loop (+ i 1))))))
+            (loop 1)
+            m))))))
+
+(define lua-math-fmod
+  (fn (a b) (- a (* b (if (> b 0) (floor (/ a b)) (ceil (/ a b)))))))
+
+(define lua-math-modf
+  (fn (x)
+    (let ((i (if (>= x 0) (floor x) (ceil x))))
+      (list (quote lua-multi) i (- x i)))))
+
+(define __rand-scale 1048576)
+(define lua-math-random
+  (fn (&rest args)
+    (cond
+      ((= (len args) 0)
+        (/ (random-int 0 (- __rand-scale 1)) (* 1.0 __rand-scale)))
+      ((= (len args) 1) (random-int 1 (first args)))
+      (else (random-int (first args) (nth args 1))))))
+
+(define lua-math-randomseed (fn (s) nil))
+
+(dict-set! math "pi" lua-math-pi)
+(dict-set! math "huge" lua-math-huge)
+(dict-set! math "abs" lua-math-abs)
+(dict-set! math "ceil" lua-math-ceil)
+(dict-set! math "floor" lua-math-floor)
+(dict-set! math "sqrt" lua-math-sqrt)
+(dict-set! math "exp" lua-math-exp)
+(dict-set! math "log" lua-math-log)
+(dict-set! math "log10" lua-math-log10)
+(dict-set! math "pow" lua-math-pow)
+(dict-set! math "sin" lua-math-sin)
+(dict-set! math "cos" lua-math-cos)
+(dict-set! math "tan" lua-math-tan)
+(dict-set! math "asin" lua-math-asin)
+(dict-set! math "acos" lua-math-acos)
+(dict-set! math "atan" lua-math-atan)
+(dict-set! math "atan2" lua-math-atan2)
+(dict-set! math "deg" lua-math-deg)
+(dict-set! math "rad" lua-math-rad)
+(dict-set! math "min" lua-math-min)
+(dict-set! math "max" lua-math-max)
+(dict-set! math "fmod" lua-math-fmod)
+(dict-set! math "modf" lua-math-modf)
+(dict-set! math "random" lua-math-random)
+(dict-set! math "randomseed" lua-math-randomseed)
diff --git a/lib/lua/test.sh b/lib/lua/test.sh
index dafd2e78..1cccca81 100755
--- a/lib/lua/test.sh
+++ b/lib/lua/test.sh
@@ -768,6 +768,42 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 1181)
 (eval "(lua-eval-ast \"return string.format(\\\"%d%%\\\", 50)\")")
 
+;; ── Phase 6: math library ─────────────────────────────────────
+(epoch 1200)
+(eval "(lua-eval-ast \"return math.pi > 3.14 and math.pi < 3.15\")")
+(epoch 1201)
+(eval "(lua-eval-ast \"return math.huge > 1000000\")")
+(epoch 1210)
+(eval "(lua-eval-ast \"return math.abs(-7)\")")
+(epoch 1211)
+(eval "(lua-eval-ast \"return math.sqrt(16)\")")
+(epoch 1212)
+(eval "(lua-eval-ast \"return math.floor(3.7)\")")
+(epoch 1213)
+(eval "(lua-eval-ast \"return math.ceil(3.2)\")")
+(epoch 1220)
+(eval "(lua-eval-ast \"return math.max(3, 7, 1, 4)\")")
+(epoch 1221)
+(eval "(lua-eval-ast \"return math.min(3, 7, 1, 4)\")")
+(epoch 1230)
+(eval "(lua-eval-ast \"return math.pow(2, 8)\")")
+(epoch 1231)
+(eval "(lua-eval-ast \"return math.exp(0)\")")
+(epoch 1232)
+(eval "(lua-eval-ast \"return math.log(1)\")")
+(epoch 1233)
+(eval "(lua-eval-ast \"return math.log10(100)\")")
+(epoch 1240)
+(eval "(lua-eval-ast \"return math.sin(0) + math.cos(0)\")")
+(epoch 1250)
+(eval "(lua-eval-ast \"return math.fmod(10, 3)\")")
+(epoch 1251)
+(eval "(lua-eval-ast \"local i, f = math.modf(3.5) return i\")")
+(epoch 1260)
+(eval "(lua-eval-ast \"local r = math.random(100) return r >= 1 and r <= 100\")")
+(epoch 1261)
+(eval "(lua-eval-ast \"local r = math.random(5, 10) return r >= 5 and r <= 10\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -1151,6 +1187,25 @@ check 1170 "string.gmatch iterator"         '3'
 check 1180 "string.format %s=%d"            '"x=42"'
 check 1181 "string.format %d%%"             '"50%"'
 
+# ── Phase 6: math library ─────────────────────────────────────
+check 1200 "math.pi in range"               'true'
+check 1201 "math.huge big"                  'true'
+check 1210 "math.abs(-7)"                   '7'
+check 1211 "math.sqrt(16)"                  '4'
+check 1212 "math.floor(3.7)"                '3'
+check 1213 "math.ceil(3.2)"                 '4'
+check 1220 "math.max(3,7,1,4)"              '7'
+check 1221 "math.min(3,7,1,4)"              '1'
+check 1230 "math.pow(2,8)"                  '256'
+check 1231 "math.exp(0)"                    '1'
+check 1232 "math.log(1)"                    '0'
+check 1233 "math.log10(100)"                '2'
+check 1240 "math.sin(0)+math.cos(0)"        '1'
+check 1250 "math.fmod(10,3)"                '1'
+check 1251 "math.modf(3.5) int part"        '3'
+check 1260 "math.random(n) in range"        'true'
+check 1261 "math.random(m,n) in range"      'true'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL Lua-on-SX tests passed"
diff --git a/plans/lua-on-sx.md b/plans/lua-on-sx.md
index d9dbb099..4e8f7b5f 100644
--- a/plans/lua-on-sx.md
+++ b/plans/lua-on-sx.md
@@ -69,7 +69,7 @@ Each item: implement → tests → tick box → update progress log.
 
 ### Phase 6 — standard library
 - [x] `string` — `format`, `sub`, `find`, `match`, `gmatch`, `gsub`, `len`, `rep`, `upper`, `lower`, `byte`, `char`
-- [ ] `math` — full surface
+- [x] `math` — full surface
 - [ ] `table` — `insert`, `remove`, `concat`, `sort`, `unpack`
 - [ ] `io` — minimal stub (read/write to SX IO surface)
 - [ ] `os` — time/date subset
@@ -82,6 +82,7 @@ Each item: implement → tests → tick box → update progress log.
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-24: lua: `math` lib — pi/huge + abs/ceil/floor/sqrt/exp/log/log10/pow/trig (sin/cos/tan/asin/acos/atan/atan2)/deg/rad/min/max (&rest)/fmod/modf/random (0/1/2 arg)/randomseed. Most ops delegate to SX primitives; log w/ base via change-of-base. 309 tests.
 - 2026-04-24: lua: `string` lib — len/upper/lower/rep/sub (1-idx + neg)/byte/char/find/match/gmatch/gsub/format. Patterns are literal-only (no `%d`/etc.); format is `%s`/`%d`/`%f`/`%%` only. `string.char` uses printable-ASCII lookup + tab/nl/cr. 292 tests.
 - 2026-04-24: lua: phase 5 — coroutines (create/resume/yield/status/wrap) via `call/cc` (perform/cek-resume not exposed to SX userland). Handles multi-yield + final return + arg passthrough. Fix: body's final return must jump via `caller-k` to the **current** resume's caller, not unwind through the stale first-call continuation. 273 tests.
 - 2026-04-24: lua: generic `for … in …` — parser split (`=` → num, else `in`), new `lua-for-in` node, transpile to `let`-bound `f,s,var` + recursive `__for_loop`. Added `ipairs`/`pairs`/`next`/`lua-arg` globals. Lua fns now arity-tolerant (`&rest __args` + indexed bind) — needed because generic for always calls iter with 2 args. Noted early-return-in-nested-block as pre-existing limitation. 265 tests.