Distance between 2 points in 3D

Math and Physics Programming

Started by travikk July 11, 2008 06:12 AM

3 comments, last by h3ro 15 years, 9 months ago

travikk

115

Author

July 11, 2008 06:12 AM

Hello there! From the basics, i know, that we can calculate distance between 2 points in 2D using the:

distance = sqrt( (x2 - x1)^2 + (y2 - y1)^2 )

That is simple, isn't it? The problem( for me ), is how to do it when we are using 3-dimensional coordinates? A(x1, y1, z1) and B(x2, y2, z2) ? regards

ToohrVyk

1,596

July 11, 2008 06:19 AM

Add " + (z2 - z1)^2" inside the square root.

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travikk

115

Author

July 11, 2008 06:20 AM

Thought about the same, but wasn't sure. Thanks.

ROBERTREAD1

100

July 11, 2008 06:41 AM

Remember SQRT is an expensive operation.

If you are comparing distances it's quicker to compare the Squared distances.

i.e.

If SQRT((x1-x2)^2+(y1-y2)^2+(z1-z2)^2) > 10 Then
...

becomes

If (x1-x2)^2+(y1-y2)^2+(z1-z2)^2 > 100 Then

I hope this is useful!