Home > src > demos > reentry_demo > reentry_dh_dx.m

# reentry_dh_dx

## PURPOSE

Jacobian of the measurement model function in reentry demo.

## SYNOPSIS

function dy = reentry_dh_dx(x,param)

## DESCRIPTION

` Jacobian of the measurement model function in reentry demo.`

## CROSS-REFERENCE INFORMATION

This function calls:
This function is called by:
• reentry_demo % Discrete-time reentry dynamics demonstration with non-linear filters

## SOURCE CODE

```0001 % Jacobian of the measurement model function in reentry demo.
0002
0003 %
0004 % Copyright (C) 2005-2006 Simo S�kk�%               2007      Jouni Hartikainen
0005 %
0007 % Licence (version 2 or later); please refer to the file
0008 % Licence.txt, included with the software, for details.
0009
0010 function dy = reentry_dh_dx(x,param)
0011
0012   xr = param{1};
0013   yr = param{2};
0014
0015   y = zeros(2,size(x,2));
0016   y(1,:) = sqrt((x(1,:) - xr).^2 + (x(2,:) - yr).^2);
0017   y(2,:) = atan2(x(2,:) - yr, x(1,:) - xr);
0018
0019   dy = zeros(2,size(x,1));
0020
0021   dy(1,1) = (x(1) - xr) / y(1);
0022   dy(1,2) = (x(2) - yr) / y(1);
0023   dy(2,1) = -(x(2)-yr) / ((x(1) - xr)^2 + (x(2) - yr)^2);
0024   dy(2,2) = (x(1)-xr) / ((x(1) - xr)^2 + (x(2) - yr)^2);
0025```

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