## Analytical tools and Matlab utilities from the FDC toolbox

The FDC toolbox makes use of the standard Simulink integrators for simulations and two dedicated Matlab programs for the determination of linearized aircraft models and steady-state trimmed flight conditions. The source files of these programs can be found in the FDC subdirectory PROGRAMS.

- ACTRIM computes trimmed-flight conditions for the non-linear Beaver model, or any other aircraft model that uses the same inputs and state variables as that system. The files ACCONSTR.M and ACCOST.M are subfunctions of this program.
- ACLIN linearizes the aircraft model around a user-specified operating point and gives the user the opportunity to select a subset of the state equations from the linearized model. It uses the Simulink program LINMOD for the actual linearization process.

Another analytical tool is SYSTPROP, which can be used to quickly find some important parameters of linear state-space systems or transfer functions. The macro's RESULTS and RESPLOT simplify processing of simulation results. FIXSTATE is a companion program for the block XFIX within the Beaver model; it sets the xfix variable in the workspace.

Furthermore, several support utilities can be found in the PROGRAMS subdirectory:

- FDCINIT initializes the Matlab search-path for the FDC toolbox and allows modification of this search path if the user e.g. would wish to edit or expand the toolbox.
- DATLOAD, LINLOAD, MATLOAD, and TRILOAD make it easy to transfer datafiles of the types *.dat, *.lin, *.mat, and *.tri from the FDC data-directory (or other directories) to the Matlab workspace. These macro's all depend on the generic load function FDCLOAD.
- DATADIR and HELPDIR determine the location of FDC datafiles and helpfiles, respectively. These macro's depend on the general directory-specification function FDCDIR.
- BROWSE is a handy command for displaying HTML help-texts (such as the one you are reading now) in a webbrowser or the Matlab help browser.
- NEWMSGBOX creates nicely-formatted message-boxes.
- NUM2STR2 is a variation on the standard NUM2STR command to pretty-print numericals.
- SCREENSIZE determines the size of your screen for the positioning of UI elements.
- TXTMENU can be used to display a menu of choices in the Matlab command-window (suppressing the default GUI behaviour of the standard MENU command).

See the table of contents for a complete overview of the FDC help information.