math/big: typo in documentation for Int.Exp

[hallazzang]

go/src/math/big/int.go

Lines 467 to 473 in 97711bf

	// Exp sets z = x**y mod |m| (i.e. the sign of m is ignored), and returns z.
	// If m == nil or m == 0, z = x**y unless y <= 0 then z = 1. If m > 0, y < 0,
	// and x and n are not relatively prime, z is unchanged and nil is returned.
	//
	// Modular exponentiation of inputs of a particular size is not a
	// cryptographically constant-time operation.
	func (z *Int) Exp(x, y, m *Int) *Int {

On line 469, it says ... x and n are not relatively prime, ... but there's no n in anywhere.
It should be m instead.

[randall77]

While someone is here, it says both m>0 and the sign of m is ignored. That first part should probably be m != 0.

[hallazzang]

@randall77 maybe just removing that (i.e. the sign of m is ignored) is fine enough?

[randall77]

I guess it all depends on what it actually does for m<0.

[gopherbot]

Change https://golang.org/cl/227998 mentions this issue: math/big: fix typo in documentation for Int.Exp

[hallazzang]

I think leaving (i.e. the sign of m is ignored) and change m > 0 to m != 0 makes much sense.

[gopherbot]

Change https://golang.org/cl/228000 mentions this issue: math/big: fix typo in documentation for Int.Exp