From d77dc25af4149487da823dd3b4588fb9cf170380 Mon Sep 17 00:00:00 2001
From: Matthew Nibecker <hello@mattnibecker.com>
Date: Mon, 29 Dec 2025 13:58:57 -0800
Subject: [PATCH] sam: Divide by float 0 returns +/-Inf

---
 book/src/command/super.md                     | 10 +++++-----
 runtime/sam/expr/eval.go                      |  6 +-----
 runtime/ztests/expr/arith-divide-by-zero.yaml |  6 ++++++
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/book/src/command/super.md b/book/src/command/super.md
index 3f624a2624..5cb335f268 100644
--- a/book/src/command/super.md
+++ b/book/src/command/super.md
@@ -500,18 +500,18 @@ or trying to debug a halted query with a vague error message.
 
 For example, this query
 ```mdtest-command
-echo '1 2 0 3' | super -s -c '10.0/this' -
+echo '1 2 0 5' | super -s -c '10/this' -
 ```
 produces
 ```mdtest-output
-10.
-5.
+10
+5
 error("divide by zero")
-3.3333333333333335
+2
 ```
 and
 ```mdtest-command
-echo '1 2 0 3' | super -c '10.0/this' - | super -s -c 'is_error(this)' -
+echo '1 2 0 5' | super -c '10/this' - | super -s -c 'is_error(this)' -
 ```
 produces just
 ```mdtest-output
diff --git a/runtime/sam/expr/eval.go b/runtime/sam/expr/eval.go
index c3893e913c..483c65484a 100644
--- a/runtime/sam/expr/eval.go
+++ b/runtime/sam/expr/eval.go
@@ -522,11 +522,7 @@ func (d *Divide) Eval(this super.Value) super.Value {
 		}
 		return super.NewInt(typ, toInt(lhsVal)/v)
 	case super.IsFloat(id):
-		v := toFloat(rhsVal)
-		if v == 0 {
-			return d.sctx.NewError(DivideByZero)
-		}
-		return super.NewFloat(typ, toFloat(lhsVal)/v)
+		return super.NewFloat(typ, toFloat(lhsVal)/toFloat(rhsVal))
 	}
 	return d.sctx.NewErrorf("type %s incompatible with '/' operator", sup.FormatType(typ))
 }
diff --git a/runtime/ztests/expr/arith-divide-by-zero.yaml b/runtime/ztests/expr/arith-divide-by-zero.yaml
index c18f4d6559..27f8c214dd 100644
--- a/runtime/ztests/expr/arith-divide-by-zero.yaml
+++ b/runtime/ztests/expr/arith-divide-by-zero.yaml
@@ -6,6 +6,8 @@ input: |
   {a:null::uint64,b:0::uint64}
   {a:2::uint64,b:null::uint64}
   {a:5::uint64,b:0::uint64}
+  {a:1.,b:0.}
+  {a:-1.,b:0.}
 
 output: |
   null::uint64
@@ -14,3 +16,7 @@ output: |
   null::uint64
   error("divide by zero")
   error("divide by zero")
+  +Inf
+  error("type float64 incompatible with '%' operator")
+  -Inf
+  error("type float64 incompatible with '%' operator")