Please address my problem

for the following code

function [sys,x0,str,ts] = Three_Tank(t,x,u,flag)

switch flag,

case 0,

    [sys,x0,str,ts] = mdlInitializeSizes;

case 1,
  sys = mdlDerivatives(t,x,u);
case 2,
  sys = mdlUpdate(t,x,u);

case 3,
  sys = mdlOutputs(t,x,u);
case 4,
  sys = mdlGetTimeOfNextVarHit(t,x,u);

case 9,
  sys = mdlTerminate(t,x,u);
otherwise
  error(['Unhandled flag = ',num2str(flag)]);

end

I am getting this error

Input argument "flag" is undefined.

Error in ==> Three_Tank at 3 switch flag

Error in ==> load_system at 34 feval(sys);

Error in ==> getLinNormalModeBlocks at 22 load_system(mdl);

Error in ==> dlinmod at 107 [normalblks,normalrefs] = getLinNormalModeBlocks(model);

Answer 1

[Friedrich]

Your function is not wrong. I think the problem is related to the way the function is called. The error indicates a call like

[sys,x0,str,ts] = Three_Tank(t,x,u)

[Krishna Kumar Kottakki]

sorry Friedrich,

still it's not working.

[Friedrich]

It must be something like this. look at this

function repro( x,y,flag )

switch flag

case 1

disp('1')

otherwise

disp('otherwise')

end

end

>> repro(1,2,1)

1

>> repro(1,2)

??? Input argument "flag" is undefined.

Error in ==> repro at 3

switch flag

[Jan]

@Krishna: The error message says, that the 4th input "flag" is not defined. You call this function by "feval(sys)" - I assume "sys" is the function handle an you submit no inputs, but Three_Tank needs 4 inputs.

Therefore I think Friedrichs answer is correct. +1

[Sean de Wolski]

@Friedrich: was that the episode where Homer had the crayon removed?

[Friedrich]

yes it was. its a screen from the scene where homer tries to say the Pythagorean theorem and fail totally.

[Sean de Wolski]

Excelllllent /...\