Unit error when using delay

[Hamilton]

Hi.

Consider the attached model. When I use a dimensionless auxiliary variable with a delay function I got this kind of message regarding error on units:

***********************************************
Error in units for the following equation:
#Auxiliary variable>DELAY3>LV2# =
INTEG( #Auxiliary variable>DELAY3>RT1#
- #Auxiliary variable>DELAY3>RT2# ,
#Auxiliary variable>DELAY3>LV3# )
#Auxiliary variable>DELAY3>LV2# --> Dmnl
#Auxiliary variable>DELAY3>RT1# --> Dmnl
#Auxiliary variable>DELAY3>RT2# --> Dmnl
#Auxiliary variable>DELAY3>LV3# --> Dmnl

Analysis of units error:
Units missmatch in INTEG
#Auxiliary variable>DELAY3>RT1#
- #Auxiliary variable>DELAY3>RT2#
Has Units: Month
#Auxiliary variable>DELAY3>LV3#
Has Units: Dimensionless

***********************************************

What I get from this message is that a delay function implies some kind of temporal unit and this causes the error. How can I correct it?

Thank you.

[tomfid]

The delay duration has units of months. When it's buried in an equation as a number (12), it's effectively dimensionless, so you need to pull it out as a named variable with units, which also has the benefit of exposing the assumption to testing. There were two other implicit parameters in the model. See attached.

unit problem 2.mdl

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[Hamilton]

Dear Tom,

Thank you so much!