# vec2pix

Convert cartesian direction vectors to MEALPix pixel numbers

## Contents

- Syntax
- Input Arguments
- Return Arguments
- Example
- See also
- Requires

## Syntax

    nPix = vec2pix(nSide,xyz,'Param1',Value1,...);

## Input Arguments

    nSide     HEALPix resolution parameter
    xyz       cell array of [3,1] cartesian direction vectors

    Param     Value
    'nest'    use nested indexing (true | {false})

## Return Arguments

    nPix      size(xyz) pixel number array

## Example

Find pixels corresponding to a [4,5] set of (unnormalized) cartesian vectors:

    nSide = 4;
    xyz0 = squeeze(num2cell(2*rand(3,4,5)-1,1));
    nPix = vec2pix(nSide,xyz0)

    % Find the normalized vectors corresponding to the pixels
    xyz1 = pix2vec(nSide,nPix);

    % Find angular distance from vectors to pixels
    d = angDist(xyz0,xyz1)

    nPix =

        28   157     2   112    58
       120    37    44   140   153
        82   121    68   127    25
       165    29    51   140    42

    d =

        0.1107    0.0752    0.1586    0.0250    0.1124
        0.0695    0.1483    0.1005    0.1260    0.1347
        0.0588    0.0572    0.0838    0.1210    0.0761
        0.1156    0.1455    0.1688    0.0376    0.1256

## See also

ang2pix, pix2ang, pix2vec

## Requires

ring2nest

Copyright 2010-2011 Lee Samuel Finn. Terms of Use.