# restrictCDtoROI

Restricts the CD to ROI.

## Contents

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

## Syntax

    y = restrictCDtoROI(x,ROImask)

## Description

`y = restrictCDtoROI(x, ROImask)` restricts the vector (or matrix) `x` in the computational domain (CD) to the region of interest (ROI), where `ROImask` is logical to describe ROI inside CD.

## Examples

Example 1: x is a vector

    x = [0 0 0 0 0 1 2 0 0 3 4 0 0 0 0 0];
    ROImask = logical([0 0 0 0; 0 1 1 0; 0 1 1 0; 0 0 0 0]);
    y = restrictCDtoROI(x,ROImask);

Result:

    y =

          1     2     3     4

Example 2: x is a matrix

    x = [0 0 0 0; 0 1 2 0; 0 3 4 0; 0 0 0 0];
    ROImask = logical([0 0 0 0; 0 1 1 0; 0 1 1 0; 0 0 0 0]);
    y = restrictCDtoROI(x,ROImask);

Result:

    y =

       1
       3
       2
       4

## Input Arguments

- x : a vector or a matrix; in this framework x is the contrast in CD written as vector of size nCD^seti.dim x 1.
- ROImask : mask (logical matrix of size seti.nCD x seti.nCD) to describe ROI inside CD by 1-entries; in this framework we define seti.ROImask, see setGrid.html

## Output Arguments

- y : CD restricted to ROI (The resut is always a vector of size nROI^seti.dim x 1.)

## See Also

- extendROItoCD.html

## Code

    function y = restrictCDtoROI(x, ROImask)
    y = x(ROImask(:));
    end