PULSe in Matlab Symbolic

Hi,

I have a approximation of a rectangular function:

function current=pulse(t)
if (t-2.5*round(t/2.5-0.5))<=0.2
    current=0.001;
else 
    current=0;
end
end

Then I need t as symbolic:

syms t;

pulse(t);

BUT I get this ERROR:

Conversion to logical from sym is not possible.

Error in ie1 (line 6)
if (t-2.5*round(t/2.5-0.5))<=0.2

Hope somebody can help. Thank you!

Answer 1

[Walter Roberson]

You will have to construct a piecewise function. See http://www.mathworks.com/help/toolbox/mupad/stdlib/piecewis.html.

Note that the MuPAD piecewise() function does not have a MATLAB interface, so you will need to use evalin(symengine) or feval(symengine) in order to create the object.

[John Miller]

Thank you but I dont get it... For example this is not working:

syms x

evalin(symengine)

pw:=piecewise([x > 0 and x < 1, 1], [Otherwise, 0]);

I have no idea how to write it down..;(

[Walter Roberson]

pw = evalin(symengine, 'piecewise([x > 0 and x < 1, 1], [Otherwise, 0])');

[John Miller]

Thank you!

I have another problem: I need a pulse function which I can use in fsolve for lets say f=x1+pulse(x2)=0

Any Idea?

[Walter Roberson]

pulsefun = matlabFunction(pulse);

fsolve( @(x) x(1) + pulsefun(x(2)), x0 )