# dS3D

Approximation of the infinitesimal element of a closed contour with control points.

## Contents

- Syntax
- Description
- Input Arguments
- Output Arguments
- See Also
- Code

## Syntax

    dS = dS3D(Nb, rad)

## Description

`dSp = dS3D(Nb, rad)` computes approximation of the infinitesimal element on a surface containing points in three dimensional space.

Currently, it is only written for spheres with radius rad on which Nb points are arranged on.

For simplicity, uniform points on surface are assumed.

## Input Arguments

- Nb : Number of points.
- rad : Radius of sphere transmitters are arranged on.

## Output Arguments

- dS : Approximation of the infinitesimal element of a closed contour with control points. Because assumption of uniform points dS is a value. If input is only one point, it is set dS = 1 (a closed contour does not make sense).

## See Also

- dS2D.html
- expSetup.html

## Code

    function dS = dS3D(Nb, rad)

    if Nb == 1
        dS = 1;
    elseif Nb > 1
        % For simplicity, assume uniform points on surface
        dS = 4*pi*rad^2/Nb;
    else
        disp('Error in function dS3D.m: size of input array too small.')
    end

    end