Script function

world.MtRand

Type

Method

Summary

Returns pseudo-random number using the Mersenne Twister algorithm

Prototype

double MtRand();

Description

This returns a pseudo-random number in the range 0 to 1 (however excluding 1) as a "double" (floating-point number). Thus you can generate a number in any range by multiplying the result by the range you want.

eg.

print (math.floor (MtRand () * 5)) - returns 0 to 4

See below in the Lua section for an example of doing coin flips.

Note that the MT generator is "global" to all of MUSHclient. If you are trying to reproduce a sequence, then you cannot rely on a sequence staying stable from one script call to another (since another script, or another world or plugin, might also use random numbers).

This (Lua) script here, for example, would generate a million random numbers, and put them into a table for later use:

nums = {} -- empty table

MtSrand (1234567) -- start with a known seed

for j = 1, 1000000 do
table.insert (nums, MtRand ())
end

This took about a second to execute on my PC.

Over a run of 10,000,000 coins flips it seemed pretty accurate, giving 5,000,625 heads and 4,999,375 tails (in other words, around 50.00625% heads).

Example (in Lua) of rolling a 6-sided die:

for i = 1, 100 do
Tell (math.floor (MtRand () * 6) + 1, " ")
end

In the above example, multiplying by 6 gives a number in the range 0 to 5, and then we add 1 to make it 1 to 6.


For more details about the Mersenne Twister see:

http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html

Available in MUSHclient version 3.57 onwards.

VBscript example

Note MtRand

Jscript example

Note (MtRand ())

Lua example

heads = 0
tails = 0

for j = 1, 1000000 do
  i = math.floor (MtRand () * 2)
  if i == 0 then
    heads = heads + 1
  else
    tails = tails + 1
  end  -- if
end  -- for

print ("heads = ", heads) --> 498893
print ("tails = ", tails) --> 501107

Return value

A pseudo-random number in the range [0 to 1). In other words, zero might be returned, however 1 will not be.

To put it another way, the returned number is:

>= 0 and < 1

See Also ...

Topics

Scripting
Utilities

Functions

(AddFont) Adds a custom font for use by MUSHclient
(Base64Decode) Takes a base-64 encoded string and decodes it.
(Base64Encode) Encodes a string using base-64 encoding.
(BlendPixel) Blends a single pixel with another, using a specified blending mode
(ChangeDir) Changes the MUSHclient working directory
(CreateGUID) Creates a GUID - Global Unique Identifier
(EditDistance) Returns the Levenshtein Edit Distance between two words
(ErrorDesc) Converts a MUSHclient script error code into an human-readable description
(ExportXML) Exports a world item in XML format
(FilterPixel) Performs a filtering operation on one pixel
(FixupEscapeSequences) Converts "escape sequences" like \t to their equivalent codes.
(FixupHTML) Fixes up text for writing as HTML
(FlashIcon) Flashes the MUSHclient icon on the Windows taskbar
(GenerateName) Generates a random character name
(GetClipboard) Gets the clipboard contents
(GetScriptTime) Returns the amount of time spent in script routines
(GetSoundStatus) Gets the status of a sound started by PlaySound
(GetUniqueID) Creates a unique ID for general use, or for making Plugin IDs
(GetUniqueNumber) Returns a unique number
(Hash) Produces a hash (checksum) of a specified piece of text
(Help) Shows help for a script function, or a list of functions
(ImportXML) Imports configuration data in XML format
(Menu) Creates a pop-up menu inside the command window
(Metaphone) Returns the metaphone code for the supplied word
(MoveMainWindow) Move and resize the main MUSHclient window
(MoveWorldWindow) Move and resize a world window
(MoveWorldWindowX) Move and resize a specific world window
(MtSrand) Seed the Mersenne Twister pseudo-random number generator
(PlaySound) Plays a sound using DirectSound
(ReadNamesFile) Loads in a file for generating character names
(Replace) Replaces one substring with another
(SetBackgroundColour) Sets a background colour for the output window
(SetBackgroundImage) Sets a background image for the output window
(SetClipboard) Sets the clipboard contents
(SetForegroundImage) Sets a foreground image for the output window
(SetMainTitle) Sets the main output window title
(SetSelection) Sets a selection range in the output window
(SetStatus) Sets the status line text
(SetTitle) Sets the world window title
(SetToolBarPosition) Sets the position of the game toolbars on the screen.
(SetUnseenLines) Sets the number of "unseen lines" for this world
(ShiftTabCompleteItem) Adds an item to the list shown for Shift+Tab completion
(Simulate) Simulate input from the MUD, for debugging purposes
(Sound) Plays a sound
(StopSound) Stop playing a sound started by PlaySound
(StripANSI) Strips ANSI colour sequences from a string
(Trace) Trace mode property
(TraceOut) Outputs the supplied message to the world Trace
(TranslateDebug) Sends a debugging message to the localizing translator script
(TranslateGerman) Translate German umluat sequences
(Transparency) Sets the transparency of the main MUSHclient window under Windows XP
(Trim) Trims leading and trailing spaces from a string

(Help topic: function=MtRand)