How to apply If else Condition in simulink?

Hi,

I want to apply an ifelse condition in simulink. How can I do that? There is a if block I can see in library but I am not sure whether it can compare it's input or not. Its showing me an syntax error massage.

In my model I have three outputs(amplitude values of some frequencies after doing fft and some other operations). For example, the amplitude values are 15, 20 and 25 corresponding frequencies are 1,2 and 3. After comparing them I want to display (using a display block) that 3 is the max frequency. Its very basic I know but I am very in in simulink. Any help would be so much appreciated. Thanks in advance.

Answer 1

[Azzi Abdelmalek]

Look at http://www.mathworks.com/help/simulink/slref/if.html

[M. Riadh Arefin]

using this if block can I compare three inputs like u1>u2 && u1>u3 (not putting values like u1>20)? And how can I show that if u1 is greater then the output is f1 (3 hz).so that I can see 3 hz in my display block. Thanks in advance.