Campbell CR9000, Instruction Manual

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Section 8. Processing and Math Instructions
8-3
Atn()
Returns the arctangent of a number.
Syntax
Atn(
number
)
Remarks
The argument number can be any valid numeric expression.
The Atn function takes the ratio ( number ) of two sides of a right triangle and
returns the corresponding angle. The ratio is the length of the side opposite the
angle divided by the length of the side adjacent to the angle. The result is
expressed in radians and is in the range -Pi/2 to Pi/2 radians. Pi is approximately
3.141593.
To convert degrees to radians, multiply degrees by Pi/180. To convert radians to
degrees, multiply radians by 180/Pi.
Note Atn is the inverse trigonometric function of Tan, which takes an angle as
its argument and returns the ratio of two sides of a right triangle. Do not
confuse Atn with the cotangent, which is the simple inverse of a tangent
(1/tangent).
Atn FunctionExample
The example uses Atn to calculate Pi. By definition, Atn(1) is 45 degrees; 180
degrees equals Pi radians.
Dim Pi 'Declare variables.
Pi = 4 * Atn( 1 ) 'Calculate Pi.
Spatial Average
Computes the spatial average of a measurement.
Syntax
AvgSpa(
Dest, Swath, Source
)
Remarks
Find the average of the values in the given array and place the result in the variable
named in Dest. The Source must be a particular element in an array (e.g., Temp(1));
it is the first element in the array to include in the average. The Swath is the
number of elements to include in the average.
Dest
X i
swath
i j
i j swath
=
=
= +
∑
( )
Where X(j) = Source
Parameter
& Data Type
Enter
AvgSpa Parameters
Dest
Variable
The variable in which to store the results of the instruction.
Swath
Constant
The number of values of the source array to average.
Source
Array
The name of the variable array that is the input for the instruction.