====== Tutorial 2 - Vectorizing the model ======


===== 4/7 =====

In this lesson will you learn how to add [[Material|materials]] to the model and basic use of [[Index_list|index lists]].

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**Overview**

Consider a water tank which is contaminated with not one, but many, substances.

This would mean that the number of state variables increase with every substance:

M<sub>Fish,Arsenic</sub>, M<sub>Fish,Lead</sub>, M<sub>Fish,Mercury</sub> etc.

Rather than creating copies of the [[Compartment|compartments]] and [[Transfer|transfers]] of our model, we can vectorize it. This is done by adding [[Material|material]], where each [[Material|material]] corresponds to a contaminant.

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**Adding materials**

  - Open the [[Materials_window|Materials window]] by selecting **Window | Materials** from the [[Menu_bar|menu bar]].
  - The table lists all [[Material|materials]] of the [[Model|model]] and is currently empty.
  - Create a new [[Material|Material]] by clicking the {{:New24.png|New}} button on the [[windows#Title_bar|title bar]] of this window, or right-click the window and select **Create | Material** from the pop-up menu.
  - Name the [[Material|material]] by clicking in the **Name** column and writing “Arsenic”.
  - In the unit column, enter “mg”.
  - In the same way, create [[Material|material]] for “Lead” and “Mercury”, assigning the same unit of “mg”.

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{{:tutorial_2_4_1.png|Screenshot}}\\

**Next**

  * [[Tutorial_2-Assigning_material_dependent_values|Assigning material dependent values (5/7)]]

**Previous**

  * [[Tutorial_2-Creating_transfers|Creating transfers (3/7)]]

**References**

  * [[Tutorials|Back to Tutorials]]
  * [[start|Home]]