# Math Operations

DataTable gives you an opportunity to load data stored as mathematical expressions. DataTable parses, evaluates such expressions and presents result in the related cells.

Note that this functionality won't work with the webix.env.strict enabled. By default, the flag is disabled and math is supported.

## Common (storing data as formulas)

To start parse data as mathematical expressions - just set parameter math to true (by default, it's disabled).
Columns are specified as usual.

Activating math support and parsing data as math expressions

``````var budget = [
...
{id:4, name:"France", rev:"1229000", exp:"1445000", dif:"=[:3,:2]-[:3,:3]",
date:"2009"}
];

grid = new webix.ui({
view:"datatable",
container:"box",
columns:[
],
math: true, //this parameter enables math support
data: budget
})``````

Related sample:  Using formulas

Syntax:

1. Formula must start from the '=' sign.
2. Within formulas can be used:

• basic mathematical operators, which are: +, -, /, *, (, );
• cell references;
• custom functions.

You can refer to a cell in 2 ways:

• [id, field] - takes the value from the specified field of an item with the specified id.
``````var data = [
{ id:1, num1:"67000", num2:"15000", difference:"=[1,num1]-[1,num2]"},
{ id:2, num1:"56000", num2:"11000", difference:"=[2,num1]-[2,num2]"},
{ id:3, num1:"45300", num2:"10000", difference:"=[3,num1]-[3,num2]"}
];``````
• [:row_ind, :col_ind] - the indexes of the row and column (zero-based numbering).
``````var data = [
{ id:1, num1:"67000", num2:"15000", difference:"=[:0,:1]-[:0,:2]"},
{ id:2, num1:"56000", num2:"11000", difference:"=[:1,:1]-[:1,:2]"},
{ id:3, num1:"45300", num2:"10000", difference:"=[:2,:1]-[:2,:2]"}
];``````

Note that if you use math operations in TreeTable, you can refer to rows only by their IDs, as row indexes are refreshed after each change.

You can also combine 2 variants and use [id, :col_ind] or [:row_ind, field].

``````var data = [
{ id:1, num1:"67000", num2:"15000", difference:"=[:0,num1]-[:0,num2]"},
{ id:2, num1:"56000", num2:"11000", difference:"=[:1,num1]-[:1,num2]"},
{ id:3, num1:"45300", num2:"10000", difference:"=[:2,num1]-[:2,num2]"}
];``````

You can call any custom function within a formula in case provided operations are not enough:

``````function mysum(a, b){ return a+b };
...
{ id:3, difference"=mysum([:0, :1], [:0,:2]) + 1 - [:0, :3]" }``````

## Assigning formulas while columns configuration

To apply some formula to a column you may also use attribute math while column configuring. Any formula that will be set as the value of this attribute will be applied to the entire column.

Specifying formulas while columns configuring

``````var budget = [
...
{ id:4, name:"France ", rev:"1229000", exp:"1445000", date:"2009"}
];
grid = new webix.ui({
view:"datatable",
container:"box",
columns:[
{ id:"dif",  header:"Deficit/surplus", math:"[\$r,:2] - [\$r,exp]"},
],
math: true, //this parameter enables math support
data: budget
})``````

Related sample:  Applying formulas to an entire column

Syntax:

1. Formula is written without the '=' sign.
2. The \$r keyword refers to the current row id.
3. The \$c keyword refers to the name of the current column.
4. Within formulas can be used:

• basic mathematical operators, which are: : +, -, /, *, (, ).
• cell references;
• custom functions.

You can refer to a cell in 2 ways:

• [id, field] - takes the value from the specified field of an item with the specified id (see usage examples above).
• [:row_ind, :col_ind] - the indexes of the row and column (zero-based numbering).
You can also combine 2 variants and use [id, :col_ind] or [:row_ind, field].

You can call any custom function within a formula in case provided operations are not enough:

``````function mysum(a, b){ return a+b };
...
{ id:"dif", header:"", math:"mysum([\$r,:2] - [\$r,exp]) + 1 - [\$r, :3]" }``````

## Sum counter

To get the total value of some column you can use the summColumn counter (instead of a math formula), created especially for this need.
The counter is added to the footer of a column (can't be used in the header).

``````columns:[
]``````

## Editing Formulas Directly in Datatable

Math formulas are editable directly in the datatable provided that:

• editMath property is set to true value;
• datatable is editable itself;
• the column where math is used features "text" editor;
• editAction is specified;
``````view:"datatable",
columns:[
{ id:"diff", header: "Math", math:"[\$r,:2] - [\$r,exp]", editor:"text"},
],
math: true,
editable:true,
editAction:"click",
editMath:true``````

When this property is omitted, you can still open the editor for the calculated cell value and see the result of the formula in the editor input. However, changes won't be saved, since math features higher priority.