# Documentation

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# matlab.io.fits.movRelHDU

Move relative number of HDUs from current HDU

## Syntax

```htype = moveRelHDU(fptr,nmove) ```

## Description

`htype = moveRelHDU(fptr,nmove)` moves a relative number of HDUs forward or backward from the current HDU and returns the HDU type, `htype`, of the resulting HDU. The possible values for `htype` are:

 `'IMAGE_HDU'` `'ASCII_TBL'` `'BINARY_TBL'`

This function corresponds to the `fits_movrel_hdu (ffmrhd)` function in the CFITSIO library C API.

## Examples

Move through each HDU in succession, then move backwards twice by two HDUs.

```import matlab.io.* fptr = fits.openFile('tst0012.fits'); n = fits.getNumHDUs(fptr); for j = 1:n htype = fits.movAbsHDU(fptr,j); fprintf('HDU %d: "%s"\n',j,htype); end htype = fits.movRelHDU(fptr,-2); n = fits.getHDUnum(fptr); fprintf('HDU %d: "%s"\n',n,htype); htype = fits.movRelHDU(fptr,-2); n = fits.getHDUnum(fptr); fprintf('HDU %d: "%s"\n',n,htype); fits.closeFile(fptr); ```

## See Also

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