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parameter matrix and the equations it generates
Here is a complete equation parameter matrix along with the equations written from it (by clicking the [Write E Equations] button). The gray cells in the matrix contain formulas rather than numbers, a possibility for any cell in an equation matrix. The equations (one for each row in the matrix) include the equation terms shown in the column heads. Numbers in the cells have replaced the # in the column head terms. The cursor marks a cell to the left of the documented equation. The content (the equation which actually goes into the model) is shown at the top of window; it contains no variable names, only the cells references for the variable names. The strength of this equation writing system is that if you want to change an equation by changing, adding, or removing a parameter, you do so manually in the matrix and simply click the [Write E Equations] button to write the new set of equations for the sheet. As an aside, the number of digits of a parameter included in an equation matches the format of the cell containing the number. If you want to change the number of digits past the decimal point to be included, just reformat the cell containing the number and re-write the equations. In general, VORSIM’s equation writing routine is very fast. You can write all equations in an equation workbook at once by clicking the [Write – ALL Equations] button on the {Variables} sheet. If your model is very large (greater than 40 sheets in your equation workbook), some VORSIM operations, including this one, are broken up into segments to avoid Excel problems. If you have a large model, you simple follow the prompts and write your equations for all sheets in terms of 20 sheets at a time. |