Difference between revisions of "If Command"

From GeoGebra Manual
Jump to: navigation, search
Line 12: Line 12:
 
* <code>f(x) = If[x < 3 ∧ x>0, x^3]</code> yields a function that equals ''sin(x)'' for x between 0 and 3 and undefined for ''x ≥ 3'' or ''x ≤ 0''.</div>}}
 
* <code>f(x) = If[x < 3 ∧ x>0, x^3]</code> yields a function that equals ''sin(x)'' for x between 0 and 3 and undefined for ''x ≥ 3'' or ''x ≤ 0''.</div>}}
 
{{note|See section: [[Boolean values]] for the symbols used in conditional statements.}}
 
{{note|See section: [[Boolean values]] for the symbols used in conditional statements.}}
 +
==If Command in Scripting==
 +
In many programming languages '''if'' is has the meaning "If condition holds, do something; otherwise do something else". In GeoGebra, arguments of If are not commands, but values, one of which becomes the value of the result. Therefore
 +
if you want to e.g. set value of ''b'' to 2 provided ''a > 2'', correct way to do this is <code>SetValue[b,If[a>2,2,b]]</code>. The other way of nesting SetValue and If is incorrect.

Revision as of 17:19, 8 September 2011


If[Condition, Object]
Yields a copy of the object if the condition evaluates to true, and an undefined object if it evaluates to false.
If[Condition, Object a, Object b]
Yields a copy of object a if the condition evaluates to true, and a copy of object b if it evaluates to false.
Warning Warning: Both objects must be of the same type.

Conditional Functions

The If command can be used to create conditional functions. Such conditional functions may be used as arguments in any command that takes a function argument, such as Derivative, Integral, and Intersect.

Example:
  • f(x) = If[x < 3, sin(x), x^2] yields a function that equals sin(x) for x < 3 and x2 for x ≥ 3
  • f(x) = If[x < 3 ∧ x>0, x^3] yields a function that equals sin(x) for x between 0 and 3 and undefined for x ≥ 3 or x ≤ 0.
Note: See section: Boolean values for the symbols used in conditional statements.

If Command in Scripting

In many programming languages 'if is has the meaning "If condition holds, do something; otherwise do something else". In GeoGebra, arguments of If are not commands, but values, one of which becomes the value of the result. Therefore if you want to e.g. set value of b to 2 provided a > 2, correct way to do this is SetValue[b,If[a>2,2,b]]. The other way of nesting SetValue and If is incorrect.

© 2020 International GeoGebra Institute