miscellanea

i am calculating the distance between two points in 3d space using this formula:

Distance = √((distanceX*distanceX) + (distanceY*distanceY) + (distanceZ*distanceZ))

i have read (elsewhere) that taking a square root can use a lot of cpu power, and as this calculation is being done repeatedly i want to make it as efficient as possible, and perhaps explore alternative formula for this calculation.

1. is taking a square root a particularly cpu intensive calculation in maxmsp? (or is this hardware dependent?)

2. is writing a javascript function to do the calculation going to add or detract from efficiency?

i am calculating the distance between two points in 3d space using this formula: 

square-root-efficiency

If you don't need actual distance but just some distance metric, you

may nod need to take the square root but can just use the square of

distance. Otherwise, if you're doing alot of sqrt calls, perhaps you

> i am calculating the distance between two points in 3d space using this formula:

> Distance = √((distanceX*distanceX) + (distanceY*distanceY) + (distanceZ*distanceZ))

> i have read (elsewhere) that taking a square root can use a lot of cpu power, and as this calculation is being done repeatedly i want to make it as efficient as possible, and perhaps explore alternative formula for this calculation.

> 1. is taking a square root a particularly cpu intensive calculation in maxmsp? (or is this hardware dependent?)

> 2. is writing a javascript function to do the calculation going to add or detract from efficiency?

If you don't need actual distance but just some distance metric, you
may nod need to take the square root but can just use the square of
distance.  Otherwise, if you're doing alot of sqrt calls, perhaps you
can use jit.matrix.

On 3/19/07, Andrew  wrote:
>
> hi,
>
> i am calculating the distance between two points in 3d space using this formula:
>
> Distance = √((distanceX*distanceX) + (distanceY*distanceY) + (distanceZ*distanceZ))
>
> i have read (elsewhere) that taking a square root can use a lot of cpu power, and as this calculation is being done repeatedly i want to make it as efficient as possible, and perhaps explore alternative formula for this calculation.
>
> so my questions are:
>
> 1. is taking a square root a particularly cpu intensive calculation in maxmsp? (or is this hardware dependent?)
>
> and
>
> 2. is writing a javascript function to do the calculation going to add or detract from efficiency?
>
> thanks
> andrew
>


you are so right, all i need is the relative difference in a position so the actual distance is not really needed, just a number relative to this distance that can be compared to another on the same scale. so yes, i don't need to take the square root after all.

square root efficiency