How to combine function in simulink

Hello,

I have a problem in which the derivative of the entrance is a ramp function from 1 to 3 second and then step function from 3 to inf.How can i combine both of those function,i tried with puting one ramp from 1 to 3 seconds, then a ramp the opposite slope from 3 to inf and then the step function, with using 2 sums, and then i used the derivative box.But the result was no the correct.What do you recommend me to do.

Answer 1

[Walter Roberson]

https://www.mathworks.com/help/simulink/ug/select-subsystem-execution.html

Use the time as input to an If Action Subsystem