20 years old code

I have a 20 years old code which starts the simulation using

OPTIONS=[1e-3,0.01,0.1,0,0,2];
euler('shuman',Ttotal,[],OPTIONS);

euler has since changed, how do I start it now? Also there is simver(1.3), anyone know what that means?

Thank you and kind regarsd,

Nilo

[Harald]

Hi,

the only euler function I could find shipping with MATLAB returns Euler numbers or polynomials. The calling syntax suggests that the euler function in this case is a user-written one, possibly implementing Euler's method for solving ODEs.

It would be a matter of looking at the code of that euler function and possibly some trial-and-error to assist further. If you can find and provide it, also check if there is a shuman.m lurking around.

Best wishes,

Harald

[Sam Chak]

Hi @Niloufar

Without additional context, we can only speculate. However, 'Shuman' may also refer to a specific filtering technique used in computational fluid dynamics (CFD).

https://journals.ametsoc.org/view/journals/mwre/85/11/1520-0493_1957_085_0357_nmiwpi_2_0_co_2.xml

This is another version of the euler() function, but it takes only two inputs:

function Y = euler(n, x)

% EULER Euler numbers and Euler polynomials.

% Y = EULER(N, X) is the N-th Euler polynomial.

% It is defined as

% euler(n, x) = subs(diff(2*exp(x*t)/(exp(t) + 1), t, n), t, 0)

% Y = EULER(N) is the N-th Euler number.

% It is defined as

% EULER(n) = 2^n*euler(n,1/2).

% See also BERNOULLI.

% Copyright 2013 The MathWorks, Inc.

The euler() function in your case could be a user-defined function designed to represent the Euler equation in fluid dynamics.

[Niloufar]

function [ret,x0,str,ts,xts]=human(t,x,u,flag);
%HUMAN	is the M-file description of the SIMULINK system named HUMAN.
%	The block-diagram can be displayed by typing: HUMAN.
%
%	SYS=HUMAN(T,X,U,FLAG) returns depending on FLAG certain
%	system values given time point, T, current state vector, X,
%	and input vector, U.
%	FLAG is used to indicate the type of output to be returned in SYS.
%
%	Setting FLAG=1 causes HUMAN to return state derivatives, FLAG=2
%	discrete states, FLAG=3 system outputs and FLAG=4 next sample
%	time. For more information and other options see SFUNC.
%
%	Calling HUMAN with a FLAG of zero:
%	[SIZES]=HUMAN([],[],[],0),  returns a vector, SIZES, which
%	contains the sizes of the state vector and other parameters.
%		SIZES(1) number of states
%		SIZES(2) number of discrete states
%		SIZES(3) number of outputs
%		SIZES(4) number of inputs
%		SIZES(5) number of roots (currently unsupported)
%		SIZES(6) direct feedthrough flag
%		SIZES(7) number of sample times
%
%	For the definition of other parameters in SIZES, see SFUNC.
%	See also, TRIM, LINMOD, LINSIM, EULER, RK23, RK45, ADAMS, GEAR.
% Note: This M-file is only used for saving graphical information;
%       after the model is loaded into memory an internal model
%       representation is used.
% the system will take on the name of this mfile:
sys = mfilename;
new_system(sys)
simver(1.3)
...

--------------------

This is the beginning of the SHUMAN file.

euler is only called one more time as

set_param(sys,'algorithm', 'Euler')

In another file.

Thank you for your replies.

Kind regards,

Nilo

[Harald]

Hi Nilo,

Is there an euler.m associated with the project?

If you are not sure, this would be displayed when running

which euler -all

Best wishes,

Harald

[Niloufar]

Hi Harald,

>> which euler -all

C:\Program Files\MATLAB\R2023b\toolbox\symbolic\symbolic\@double\euler.m % double method

C:\Program Files\MATLAB\R2023b\toolbox\symbolic\symbolic\@single\euler.m % single method

C:\Program Files\MATLAB\R2023b\toolbox\symbolic\symbolic\@sym\euler.m % sym method

This is the output.

Kind regards,

Nilo

[dpb]

That shows only what is presently installed with the 2023b MATLAB release; not what code was part of the 20-yr ago Simulink model. You'll have to find all the old original code from that time to have any chance or reinvent whatever it was that was being modelled.

[Niloufar]

I have all of the code, could it be in eariler version it meant something else.

[dpb]

No, it doesn't appear you do have all the original code; somewhere there was another user-supplied euier function besides Mathworks-suppled one. What, specifically, it did is anybody's guess depending upon what the model is of but it's a decent bet it was an implementation of Euler's method for ODEs.

Other than "20 years ago code" is there any chance you can find out what release was installed when this was last run succcessfully? You could then verify that there was no prior functionality that matched that footprint that has subsequently been removed.

Search FEX, maybe the developer picked up a submittal from there.

[Steven Lord]

Do you have a Simulink model file for your system? If you do, what happens when you try opening it up in Simulink today? Does it know how to translate those very old pieces of infrastructure into the current Simulink architecture, does it throw errors, or does something else happen?