====== Tutorial 5 - Using a general variable ======

===== 2/5 =====

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  - Download the file {{tutorial:Soil_Dose.eco?linkonly}} and open it in Ecolego by clicking the {{:Open24.png|Open}} button, or by selecting **File | Open** from the [[Menu_bar|Menu bar]].
  - The agricultural sub-system has a transfer named “Deposition”. The deposition rate is defined as a parameter, making it impossible to run a simulation with a time-varying deposition rate – for instance contamination during a limited time. You will create a [[General_Variable|General Variable]] that allows different ways of entering values for deposition.
  - Open the [[Sub-system|sub-system]] //Agricultural Land//.
  - Rename the [[parameter|parameter]] //depRate// to //depRate_constant//.Create a [[lookup_table|lookup table]], call it //depRate_lookup//. Assign a default value of 0.
  - Create a [[General_Variable|General Variable]].
  - Edit the [[General_Variable|General Variable]].
  - Name it “depRate”.
  - Make the [[General_Variable|General Variable]] a **vector** (dimension 1-dependency)
  - In the list **Available objects**, move the [[Parameter|Parameter]] //depRate_constant// and the [[Lookup_Table|Lookup Table]] //depRate_timeseries// to the selected list using the > button.
  - Select the //depRate_constant// in the -Default- **Selected** field above. Click **Ok**.

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Edit the [[Transfer|Transfer]] //Deposition//. Choose the **Values tab**. Replace the [[Parameter|Parameter]] //depRate_constant// with the [[General_Variable|General Variable]] //depRate// in the **Expression field**.



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  * [[Tutorial_5-Packaging_the_Sub-systems|Packaging the Sub-systems (3/5)]]

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  * [[Tutorial_5-Re-useable_Components|Re-useable components (1/5)]]

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