Campbell-scientific CR9000X Measurement and Control System Uživatelský manuál stáhnout pdf (Strana 292)

Section 8. Processing and Math Instructions

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).

NOTE

ATN FunctionExample

The example uses ATN to calculate

π. By definition, ATN(1) is 45 degrees; 180

degrees equals

π radians.

Dim Pi 'Declare variables.

Pi = 4 * ATN(1) 'Calculate π.

ATN2(Source)

The ATN2 function returns the arctangent of y/x.

Syntax

x = ATN2 ( Y, X )

Remarks

ATN2 function calculates the arctangent of Y/X returning a value in the range

from

π to -π radians, using the signs of both parameters to determine the

quadrant of the return value. ATN2 is defined for every point other than the

origin (X = 0 and Y = 0). Y and X can be variables, constants, or expressions.

If it is desired to use degrees instead of radians for the inputs and results of the

trig functions in a program, the "AngleDegrees" declaration instruction can be

used.

To convert degrees to radians, multiply degrees by

π/180. To convert radians to

degrees, multiply radians by 180/

π. π is approximately 3.141593.

AvgRun (Dest, Reps, Source, Number)

AvgRun is used to calculate a running average of a measurement or calculated

value.

Syntax

AvgRun(Dest, Reps, Source, Number)

Remarks

A running average is the average of the last N values where N is the number of

values.

Dest

∑

N −1

Where is the most recent value of the source variable and is the

previous value ( is the oldest value included in the average, i.e., N-1 values

back from the most recent). NANs are not included in the processing of the

AvgRun. N (number of values used in the Running Average) will be

reduced by the number of NANs encountered in the current band of

values, reducing the number of values used in the AvgRun calculations

until the NAN(s) are cycled through.

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