index.md

---

title: Copy sign
slug: WebAssembly/Reference/Numeric/Copy_sign

---

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The copysign instructions, are used to copy just the sign bit from one number to another.

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Syntax

;; load two numbers onto the stack
f32.const 10
f32.const -1

;; copy just the sign bit from the second number (-1) to the first (10)
f32.copysign

;; the top item on the stack will now be -10

Instruction	Binary opcode
f32.copysign	0x98
f64.copysign	0xa6