11.2. Basic

AskString (query)

AskString (query, default)

Asks a question and lets the user enter a string which it then returns. If the user cancels or closes the window, then null is returned. The execution of the program is blocked until the user responds. If default is given, then it is pre-typed in for the user to just press enter on.

Compose (f,g)

Compose two functions and return a function that is the composition of f and g.

ComposePower (f,n,x)

Compose and execute a function with itself n times, passing x as argument. Returning x if n equals 0. Example:

genius> function f(x) = x^2 ;
genius> ComposePower (f,3,7)
= 5764801
genius> f(f(f(7)))
= 5764801

Evaluate (str)

Parses and evaluates a string.

GetCurrentModulo

Get current modulo from the context outside the function. That is, if outside of the function was executed in modulo (using mod) then this returns what this modulo was. Normally the body of the function called is not executed in modular arithmetic, and this builtin function makes it possible to make GEL functions aware of modular arithmetic.

Identity (x)

Identity function, returns its argument.

IntegerFromBoolean (bval)

Make integer (0 for false or 1 for true) from a boolean value. bval can also be a number in which case a non-zero value will be interpreted as true and zero will be interpretted as false.

IsBoolean (arg)

Check if argument is a boolean (and not a number).

IsDefined (id)

Check if an id is defined. You should pass a string or and identifier. If you pass a matrix, each entry will be evaluated separately and the matrix should contain strings or identifiers.

IsFunction (arg)

Check if argument is a function.

IsFunctionOrIdentifier (arg)

Check if argument is a function or an identifier.

IsFunctionRef (arg)

Check if argument is a function reference. This includes variable references.

IsMatrix (arg)

Check if argument is a matrix. Even though null is sometimes considered an empty matrix, the function IsMatrix does not consider null a matrix.

IsNull (arg)

Check if argument is a null.

IsString (arg)

Check if argument is a text string.

IsValue (arg)

Check if argument is a number.

Parse (str)

Parses but does not evaluate a string. Note that certain precomputation is done during the parsing stage.

SetFunctionFlags (id,flags...)

Set flags for a function, currently "PropagateMod" and "NoModuloArguments". If "PropagateMod" is set, then the body of the function is evaluated in modular arithmetic when the function is called inside a block that was evaluated using modular arithmetic (using mod). If "NoModuloArguments", then the arguments of the function are never evaluated using modular arithmetic.

SetHelp (id,category,desc)

Set the category and help description line for a function.

SetHelpAlias (id,alias)

Sets up a help alias.

chdir (dir)

Changes current directory, same as the cd.

display (str,expr)

Display a string and an expression with a colon to separate them.

error (str)

Prints a string to the error stream (onto the console).

exit

Aliases: quit

Exits the program.

false

Aliases: False FALSE

The false boolean value.

manual

Displays the user manual.

print (str)

Prints an expression and then print a newline. The argument str can be any expression. It is made into a string before being printed.

printn (str)

Prints an expression without a trailing newline. The argument str can be any expression. It is made into a string before being printed.

protect (id)

Protect a variable from being modified. This is used on the internal GEL functions to avoid them being accidentally overridden.

set (id,val)

Set a global variable. The id can be either a string or a quoted identifier as follows. For example:

set(`x,1)
	    

string (s)

Make a string. This will make a string out of any argument.

true

Aliases: True TRUE

The true boolean value.

undefine (id)

Undefine a variable. This includes locals and globals, every value on all context levels is wiped. This function should really not be used on local variables.

unprotect (id)

Unprotect a variable from being modified.

wait (secs)

Waits a specified number of seconds. secs must be nonnegative. Zero is accepted and nothing happens in this case, except possibly user interface events are processed.

version

Returns the version of Genius as a horizontal 3-vector with major version first, then minor version and finally patchlevel.

warranty

Gives the warranty information.