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set_column_formula [Thu Jun 7 17:20:45 2012]
Alexander
set_column_formula [Sun Nov 8 12:21:24 2015]
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-====== Setting Column Formula ====== 
-=== There are two ways to set formula for column evaluation: === 
  
-1. Select column and write formula in formula string. 
- 
-{{:​column-inspector.png?​nolink|}} 
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-2. Use ''​Table -> Set Column Formula''​ menu item to open column formula dialog window. See [[formula|formula syntax]] for details. 
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-{{:​column_formula.png?​nolink| Set column formula dialog}} 
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-===== Row Index ===== 
-Variable ''​i''​ contains the current row index. Rows are enumerated from 1. 
- 
-===== Rows Evaluation Order ===== 
-Rows are always evaluated one after another from the first to the last in the specified range. Accordingly the row number ''​i''​ is incremented after each step. 
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-== Example == 
-  * You can use this behavior to calculate [[wp>​factorial]]:​ set ''​1''​ in the first row of column ''​A''​ and after that set formula ''​cell(A,​ i-1) * i''​ and rows interval from ''​2''​ to ''​100''​. Note that formula is to be set for rows beginning from the second, and not from the first. You will get the factorial of row number (''​i''​). 
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- 
-===== Using Table Data ===== 
-There are two functions to obtain current table cell values in formula: 
-  * ''​col(A)''​ -- returns the value of cell in column ''​A''​ in the current (i-th) row. Equivalent to ''​cell(A,​ i)''​. 
-  * ''​cell(A,​ 3)''​ -- returns the value in column ''​A''​ and row ''​3''​. 
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-You can use either upper-case letters (''​A...Z'',​ e.g. ''​col(B)''​) or numbers (''​1,​ 2, 3,​..'',​ e.g. ''​col(1)''​) in columns numeration in arguments of ''​col''​ and ''​cell''​ functions. 
- 
-== Example == 
-  * ''​col(A) + 15 + cell(B, i+1)''​ 
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-===== Auto Recalculation on Data Change ===== 
-MagicPlot can automatically recalculate formula when data in used columns are changed. Set ''​Auto Recalculate''​ checkbox to enable this feature. 
- 
-== Example == 
-  * Set formula ''​col(A)*2''​ for column B and set ''​Auto Recalculate''​ checkbox. Column B will be recalculated if you change values in column A or column A is updated by other formula or processing algorithm (e.g. integral, derivative of other column). 
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-===== Formula Menu in Column Context Menu ===== 
-You can edit column formula and change auto recalculation mode from column context menu or menu ''​Table''​. Select exactly one column and open context menu to view this menu items. 
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-{{:​formula_submenu.png|Formula Menu}} 
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-===== “Argument is out of range at row #” Warning ===== 
-Some mathematical functions can be defined only on a certain interval. For example, square root (''​sqrt(x)''​) is not defined for negative numbers (all calculations in MagicPlot are made in real numbers, not complex). Hence if the argument of ''​sqrt''​ is negative, a [[nan|Not-a-Number (NaN)]] is returned. If a NaN value occurs in some part of formula, the result of calculation will also be a NaN, and corresponding table cells will be empty. 
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-The calculations are not terminated if NaN value occurs in some row(s). 
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-In some cases you may want to check if a ''​NaN''​ values occurs in calculations. MagicPlot shows the warning "//​Argument is out of range at row #//". This row number is the **first** row in which ''​NaN''​ value was returned. MagicPlot also highlights the function or operator which first produces NaN value. 
- 
-===== See Also ===== 
-  * [[formula|Formula syntax]] 
set_column_formula.txt · Last modified: Sun Nov 8 12:21:24 2015 (external edit)