Accessing Open Data
ODCalc was particularly designed to make it easy to access open sources of data for use in calculations – open data values can in most cased be obtained and used as though it were any other number or variable entered from the keyword.
Data sources come in two types – property sources and constant sources. Both types of source return primarily values that are numbers with units that can be used in maths calculations. The data sources that are available depend on the version of ODCalc and can usually be managed from the user interface. The from keyword is used to specify which data source to take the requested value from, for example the following phrase requests a value from wikipedia
It is also possible to omit the “from xyz” particle from the statement, in which case the calculator will check its default data source(s) – these are usually configurable from the user interface. Wikipedia will usually be present as a default source for general calculations.
Property Data Sources
Property data sources are able to provide pieces of information about particular entities using the of keyword, <property> of <entity>
Here the “spin” property is looked up from the source's information about the “electron” entity.
The calculator aims to make entering calculations easy so it is also ok to enter
In some cases the names of properties or entities clash with the calculator's operators and it will interpret the statement in a way that isn't what was intended – this can be overcome by enclosing the name of the property and/or entitiy in double quotes
Constant Data Sources
Constant data sources provide specific named pieces of information, particularly scientific constants