# LinkNotions: the interactive visual calculator software

## Calculate the surface area of a property

Each formula uses functions. The simplest functions are:

• subtraction (-)
• multiplication (*)
• division (/)

For details on the use of formulas and functions, please refer to the formulas page in the LinkNotions visual spreadsheet.

The formula of the surface of a field is:

Surface = Length * Width

## First way to calculate the surface of a field:

We put the value of the length in the notion “Length” and the value of the width in the notion “Width”.

The value of the surface will be calculated in the concept “Surface”.

Here is the interactive spreadsheet corresponding to it:

In the interactive diagram above click on the notion “Surface”.

You see the formula used in the “Main Expression” field of the calculations window:

#### id1 * id4

id1 is the id number of the notion “Length” (A1)

id4 is the id number of the notion “Width” (A2)

Note 1: In LinkNotions, each concept is automatically assigned an id number when it is created. This number is unique and is therefore ideal for referencing a notion in a formula. It always starts with “id”.

You will find the fixed number of a notion:

• in the tooltip by placing the cursor on the notion
• in the “Info” window at the bottom right of the screen.

Note 2: To refer a notion, you can also use the variable number (the position of the notion in the diagram: A1, A2, …) or assign to each notion a reference.

## Second way to calculate the surface area of a property :

We put all the values in the notion “Property” (A1).

The notion that is in A1 has the name “Property” (1). It has a main sub-name “Surface” (2) and two sub-names “Length” (3) and Width (4).

The sub-names are in the drop-down list (5)

The main sub-name (Surface) is 1000.
The subname (Length) is 50.
The sub-name (Width) is 20.

The value of the main subname is calculated using both sub-values.

The formula that corresponds to it is (6):

#### id1.long*id1.larg

It is in the “Main Expression” field (7) of the calculations window.

Explanations of the formula:

To be able to refer sub-names in the formula, we must assign each sub-name a subname for formulas (reference).

We have assigned the subname for formulas “long” to the subname “Length” and the subname for formulas “larg” to the subname “Width”.

To refer a sub-name of a notion one must refer the notion, followed by a point, followed by the short subname. Example: “id1.long”

The formula for the main subname is: id1.long * id1.larg. id1 is the id number of the notion “Property”.

Note that instead of the id number to refer the notion “property”, we could have taken his variable number (A2) or its reference “ter”.

#### How to proceed (detailed explanations)

In your LinkNotions account create a visual spreadsheet: click on “Create workspace” (1). In the window that opens, enter the diagram name and the number of columns (Width) and the number of rows (Height). The diagram is open.

Put the cursor on the empty square. This one becomes blue. Double-click the square. Enter the name “Property” in the window that opens (2). Click “Create” (3). The notion “Property” has been created. It is in A1 (4).

Click on notion A1, then click on the “Show / Hide Calculation Toolbar” button (5). The “calculations” window is open (6).

Enter ” surface ” in the “Main Subname display” field (7).

To access the sub-names, please pull the “Calculations” window up (8).

Click on “+” (9) and enter the first sub-name “Length” (10). Give it as a subname for formulas the word “leng” (11) and as a value (expression of the sub-name) the number 50 (12).

Click an image to enlarge. Type “Esc” on your keyboard to come back.

Click again on “+” (9). Enter the second subname “Width” (13). Give it as a subname for formulas the word “wid” (14) and as a value (expression of the subname) the number 20 (15).

You have now defined the two subnames (Length and Width).

We still have to write the formula of the surface: Length * Width.

To refer a sub-name of a notion, it is enough to refer the notion, followed by a point, followed by the reference of the subname.

We will use the id number (id1) of the notion to refer this one.

To refer to the subname “Length” we will have: id1.leng

id1 is the id number of the notion Property; leng being the reference for the subname Length.

To refer to the subname “Width” we will have: id1.wid

The formula becomes: id1.leng*id1.wid

The formula is written in the field “Main expression(16).

Now click on the “Save and Calculate” button (17).

You see the results of our inscriptions in the notion (18).