Calculating Norm(inf) within Stateflow

Hey,

I'm not sure if this is a bug, a feature or if I'm doing something wrong. I need to calculate a vector-norm (infinity) from time to time in stateflow.

I have two input-signals x1 and x2, both two rows, one column. When I pass these signals to an embedded matlab-function:

out1=calcnorm(x1, x2)

function y=calnorm(cx1, cx2)
y=norm(cx1+cx2, inf)

I'll get just the addition as a result, (again 2x1-Vector). This is still true if I'm using an embedded Simulink-Function containing an embedded Matlab-Funktion.

I found no limitations concerning norm and stateflow..

Any suggestions?

thanks frederik

edit: I'm working with Matlab R2010b

Answer 1

[Arnaud Miege]

Thanks for the additional comments. Yes, I was using only Simulink and can reproduce the problem in Stateflow. I worked around it by specifying explicitly the dimensions of the various inputs and outputs in the Model Explorer:

• At the chart level, set the dimension of b & c to 2 and the dimension of out1 to 1;
• At the Embedded MATLAB function level, set the dimensions of b1 and b2 to 2 and the dimension of y to 1.

It should work after that.

HTH,

Arnaud

Answer 2

[Arnaud Miege]

I have tried it with a MATLAB Function block (new name for Embedded MATLAB block in R2011a) and it works fine. I don't think you need the first line of the code though. Here's the code I used:

function y=calnorm(cx1, cx2)
%#codegen
  y = norm(cx1+cx2, inf);
end

The %#codegen pragma is specific to R2011a, it replaces the %#eml in previous releases. I get a scalar output with the inf norm of the sum of the two input vectors.

HTH,

Arnaud

Answer 3

[Frederik]

thanks for your answer, unfortunately this doesn't solve my problem.

Have you tried this in Simulink or in Stateflow? In Simulink this works fine.

Even with the %#eml Statement it doesn't work. Unfortunately I'm not able to attach a minimum Realization.

Thats what I've done:

Two Constant Blocks in Simulink Containing [1;2] both entering the Chart-Block (b / c) Two states a1 and a2. One transition from a1 to a2, default transition entering a1.

The only action in a1:

entry: out1 = cal(b,c)

eM-Function:

function y=cal(b1, b2)
%#eml
y=norm(b1+b2, inf)
end

there is no difference with or without the %#eml statement

no more actions. out1 is my output to my Simulink-Scope. If I limit out1 to size=1 I'll get the following Error:

Cannot reshape Input Data 'b' (#27) ([2]) to Output Data 'out1' (#43) (scalar) for operator =. Please refer to object (#19)

#19 is my state a1

even if I declare an extrinsic matlab-function and try to calculate the norm there it won't work.

thanks for your support

frederik