CONTROL
- Introduction to CTRL
- CONTROL Classes
- Types of Control Functions
- CONTROL graphics
- CONTROL Functions
  - Funtions A
  - Funtions B
  - Funtions C
  - Funtions D
  - Functions E
  - Functions F
  - Functions G
  - Functions H
  - Functions I
    - iec61850_createRcbDp()
      This function allows to create internal RCB data points.
    - iec61850_deleteRcbDp()
      Deletes the given internal RCB data point.
    - imageToFile()
      Stores an images which was created using getPanelPreview() (or using QVarPicture) to a file on the disk.
    - initializeAesPermissionCustomization()
    - initializeAesRowCustomization()
    - inputRecorderGetScript()
      The function returns the script after the recording is stopped.
    - inputRecorderIsRecording()
      The function shows if the input recorder is currently recording.
    - inputRecorderStart()
      The function starts the input recording.
    - inputRecorderStop()
      The function stops the input recording.
    - invokeMethod()
      Invokes a method of a EWO widget or of a reference created via CTRL++/OOP.
    - isAckable()
      The CTRLLib.ctl function is called before an acknowledgment with a simple configuration (see Acknowledge).
    - isAlertAttribute()
      Indicates whether the passed attribute is an alarm attribute. That means whether is can be queried with alertGetPeriod(), alertConnect(), SELECT ALERT or can be set with alertSet().
    - isAnswer()
      The function isAnswer() checks whether the workFunction() of a dpConnect() is called the first time after the connection was established via dpConnect().
    - isConnActive()
      The function checks whether the connection to the event manager is active. The function is used in split mode to determine the active EM connection. The host the user interface is logical connected to is shown in the system overview. See chapter System overview with redundancy.
    - isConnOpen()
      The function checks if the connection from the own user interface manager to the event manager exists. The function is used in a redundant system. With this function, you can find out to which event manager the UI is connected to (to the left or to the right).
    - isDbgFlag()
      Queries if a flag with the defined name or number has been set.
    - isDialog()
      Checks if a panel was opened with openDialog().
    - isdir()
      The function checks if a specified directory exists.
    - isDirectory()
      The function checks if the specified string is a directory or a file. The function returns 1 if the specified string is a directory and 0 if the specified string is a file.
    - isDistributed()
      The function returns TRUE if the entry distributed = 1 exists for the manager in the config file. If the entry distributed in the config file is not 1, FALSE will be returned. In case of a remote UI, the distributed entry is set by the Data Manager when distributed = 0/1 does not exist in the file. In this way, also other systems than the own local system can be accessed.
    - isDollarDefined()
      This function queries whether a specific dollar parameter exists.
    - isDpTypeStruct()
      Checks if a data point type is a struct type.
    - isDpTypeSumAlert()
      Checks if a sum alert or a normal alert can be configured for a data point type.
    - isEvConnOpen()
      Returns the status of the connection to the Event Manager.
    - isfile()
      The function tests if a specified file exists.
    - isFunctionDefined()
      Returns whether a specific function exists or not.
    - isInBrowser()
      Verifies whether the UI Manager is running in the Web Client plugin inside the web browser.
    - isinf()
      Indicates whether the returned value of a mathematical function is an infinite value.
    - isInstanceOf()
      This function determines if the given instance of a class is an instance of a specific class. Additionally it can be used to check if an enum is of a specific enum-type.
    - isMobileDevice()
      This function queries if the device from which the function is called is a mobile device or not.
    - isModeExtended()
      This function returns whether the Vision has been opened in extended mode (configuration mode) or not.
    - isModuleOpen()
      Specifies whether a particular module is open.
    - isMotif() - obsolete
      Specifies whether the user interface is UI Motif (obsolete as of version 3.5. The return value is always FALSE ).
    - isnan()
      Indicates whether the returned value of a mathematical function is a NaN (Not a Number).
    - isPanelInGedi()
      The function returns TRUE when the panel where the function is used is open in GEDI.
    - isPanelOpen()
      The function returns whether a particular panel is open.
    - isProgressBarOpen()
      The function checks, whether a progress bar is open.
    - isReduActive()
      Returns TRUE if the event manager to which a CTRL or UI manager is connected is currently active.
    - isReduDp()
      The function isReduDp() checks if the specified data point is redundant.
    - isRedundant()
      This function returns whether the project has been configured as redundant.
    - isRefresh()
      With the function isRefresh(), you can check whether the workFunction of a dpConnect() has been triggered by a redundancy switch or has been triggered when trying to establish a connection to a distributed system.
    - isRemoteSystemRedundant()
      This function returns whether the project has been configured as redundant.
    - isSplitModeActive()
      Returns whether split mode has been activated in the system.
    - isTableAckable()
      This libCTRL.ctl function is called before an acknowledgment of a table, when this has been realized with simple configuration. The function helps to customize a project.
  - Functions J
  - Functions K
  - Functions L
  - Functions M
  - Functions N
  - Functions O
  - Functions P
  - Functions Q
  - Functions R
  - Functions S
  - Functions T
  - Functions U
  - Functions V
  - Functions W
  - Functions X
  - Functions Y
  - Functions Z
- CTRL-Debugger
  Der CTRL-Debugger ermöglicht ein Debuggen der Pogrammiersprache Control.

isnan()

Indicates whether the returned value of a mathematical function is a NaN (Not a Number).

Synopsis

bool isnan (float x);

Parameters


Parameter	Description
x	Value to be checked.

Return Value

Returns TRUE, if the "x" value is a NaN. If the function isnan is used with a mathematical functions such as pow(-2, 0.5), it returns 0.

Description

The function checks if the specified value of the specified mathematical function is a NaN (Not a Number).

Example

main()
{
  float f;
  f=pow(2.0, 8.0); // Natural 256
  DebugN(isnan(f)); // Returns FALSE
}

Assignment

Mathematical function

Availability

CTRL