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Fix a quantity that is data in one model and a decision in another#

Write one spec in which a quantity, such as a plant's size, is chosen by the solver in one study and given by the data in another. The file stays the same in both studies, and only the data changes.

  1. Declare the quantity as a variable, with named bounds.
dimensions:
  plant: { dtype: str }
parameters:
  size_min: { dims: [plant] }
  size_max: { dims: [plant] }
variables:
  size:
    dims: [plant]
    bounds: { lower: size_min, upper: size_max }

  1. Write every rule against the variable. rate - relmax * size <= 0 is one equation whether size is chosen or given.

  2. Pin it in the data where it is given. Attach size_min and size_max as the same value for a plant whose size is fixed. Equal bounds pin a variable, which fixes it to that value (variables).

A pinned variable is still a variable, so size * on is variable * variable, and size cannot stand in the bounds: of another variable. Where a bound must use the size, attach the size as a parameter too.