# Template:Calculate increment Template documentation[view]  [history] [purge]

## Usage

This template takes two numbers and calculates a suitable increment for {{scalemarkers}} based on the difference between these numbers. Increments are 1, 2 or 5 times an appropriate power of 10.

These numbers, the from value and the to value, are input as unnamed parameters.

`{{calculate increment|`p1`|`p2`}}`

The absolute value, d, of the difference between these is calculated.

d = | p1p2 |

This can be expressed in scientific notation as follows.

d = a × 10n

Where 1 ≤ a < 10 and n is an integer.

The output of the template is as follows.

 For 1 ≤ a < 1.35 the output is the number 1 × 10n − 1 For 1.35 ≤ a < 3.45 the output is the number 2 × 10n − 1 For 3.45 ≤ a < 6.95 the output is the number 5 × 10n − 1 For 6.95 ≤ a < 10 the output is the number 1 × 10n
Note
• The values are returned as ordinary numbers (for use in other templates) not in scientific notation (e.g. 5000 not 5 × 103).
• The template code actually uses 1.4, 3.5 and 7 as cut offs but these are reduced by 0.05 due to rounding.
Examples
• `"{{calculate increment|1|5}}"` gives "0.5

" 

• `"{{calculate increment|10|20}}"` gives "1

" 

• `"{{calculate increment|10|50}}"` gives "5

" 

• `"{{calculate increment|100|250}}"` gives "20

" 

• `"{{calculate increment|1000|2000}}"` gives "100

" 

• `"{{calculate increment|2000|7500}}"` gives "500

" 

• `"{{calculate increment|100000|750000}}"` gives "50000

" 

Technical details

The main template page calculates d, the absolute value of the difference between the two inputs. Using {{order of magnitude}} the order of magnitude, n, of d is calculated. d and 10n − 1 are sent as parameters 1 and 2 respectively to a subpage, {{calculate increment/calc}}. This subtemplate uses a `#switch` to determine the correct factor, 1, 2, 5 or 10, then multiplies by 10n − 1.