What's the inverse of a square root?

[Rodéric]

Clearly this is a semantic issue and not a maths issue.

In the context of the book, I don't think it could mean that x*x or x^2 is hardware accelerated, I mean, if multiply is not hardware accelerated, then what is ?
So I think that in the context it's all about the RSQRT instruction.

(That said when I read the topic I immediatly thought about x^2, but when I read the 2nd post by K.I.L.E.R I did reconsider it and changed my mind for RSQRT instruction, given the context.)

 

[nutball]

So why is the inverse square law so called...??

/runs ... :smile:

 

[Basic]

"x>=0 is not necessary"

Yes it really is, I insist you specify an appropriate domain!

Here is the definition in pedant mode:

given a function f(x) and some domain X, the inverse function exists iff
for every x is an element of X

f^-1 (f(x)) = f (f^-1(x)) = x

Close to correct.

x>=0 is necessary in this case.
But the inverse of a function can exist even if the rule you give isn't fullfilled.

Given a function f(x), defined in a domain X, and with a range Y.
The inverse function exists iff for every x that is an element of X
f^-1 (f(x)) = x
and for every y that is an element of Y
f (f^-1) = y

Or in other words, you need a one to one mapping between domain and range, but the domain and range doesn't have to be the same.

 

[K.I.L.E.R]

Are you calling me a liar?

Clearly this is a semantic issue and not a maths issue.

In the context of the book, I don't think it could mean that x*x or x^2 is hardware accelerated, I mean, if multiply is not hardware accelerated, then what is ?
So I think that in the context it's all about the RSQRT instruction.

(That said when I read the topic I immediatly thought about x^2, but when I read the 2nd post by K.I.L.E.R I did reconsider it and changed my mind for RSQRT instruction, given the context.)

 

[ShootMyMonkey]

Are you calling me a liar?

Well... I guess the written word is really low bandwidth, 'cause I can't tell if you're being sarcastic or you're just that crazy. About the only thing you were accused of (if anything at all), was poor reading comprehension and being incomplete with your first post. And I do believe that if you seriously got "liar" out of Ingenu's post, that the reading comprehension admonishment is definitely a valid one.