[TRNSYS-users] if elseif else statement in equations

[Jeff Thornton]

Jan,

Yes it is possible but before you go down that route it’s important to understand if your variable T is impacted by the result of X.  If T is the ambient temperature for example then X doesn’t affect it and you can use equations.  If T is the temperature in a piping network and X is the flow rate then using equations will likely cause convergence errors and you are better off using differential controllers.

But if we assume that T isn’t affected by X then we simply use Boolean equations 

X1 = LT(T,5)
X2 = GE(T,5)*LT(T,15)
X3 = GE(T,15)
X = X1*1 + X2*2 + X3*3

Jeff 

Sent from my iPhone

> On Apr 7, 2022, at 7:00 AM, Böttner, Jan via TRNSYS-users <trnsys-users at lists.onebuilding.org> wrote:
> 
> 
> Hey everyone,
>  
> i found this entry about implementing if else statements: http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/2013-February/024732.html
> 
> I’m wondering if ist possible to extend this to an if elseif else statement.
> 
> I want the output X to be X=1 if the temperature is t<5, X=2 for t>=5.and.t<15 and X=3 for t>=15.
>  
> I tried this, but it’s wrong and doesnt work:
> X = GT(T,GT(T,15)*S+(1-GT(T,15))*U)*U+(1-GT(T,5))*W with S=3,U=2and W=1.
>  
> If anyone knows a solution i’d appreciate it.
>  
> Best regards
> Jan
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