CELSIUS()
 Converts a Fahrenheit temperature value into Celsius
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 Syntax

     CELSIUS(<nFahrenheit>) --> nCelsius

 Argument

     <nFahrenheit>  Designates a temperature in Fahrenheit.

 Returns

     CELSIUS() returns the converted temperature in degrees Celsius.

 Description

     This function converts Fahrenheit temperature values directly into
     Celsius values.

 Example

     Convert to Celsius:

     CODEX = CELSIUS(33.8)   // Result:  1
     CELSIUS(338.0)          // Result:  170
     CELSIUS(3380.0)         // Result:  1860
     CELSIUS(-33.8)          // Result:  -36.555555...