# System Functions

ACS( ) | Return Arc-Cosine

## Format

ACS(num[,ERR=stmtref])
Where:

num | Numeric expression (range -1 to +1) whose Arc-Cosine is to be returned.
stmtref | Program line number or statement label to which to transfer control.
#### Note: The value to be supplied must be in Radians, not Degrees. To convert Degrees to Radians: Radians = Degrees * pi / 180 Degrees = Radians * 180 / pi

## Returns

Numeric value between 0 (zero) and ð (pi=3.14159...).

## Description

The ACS( ) function returns the Arc-Cosine of the numeric expression num. It returns a value between 0 (zero) and ð (pi) rounded to the current PRECISION in effect. This is the inverse of the COS( ) function.

The value of your numeric must be in the range of -1 to +1 inclusive; otherwise, PxPlus returns an Error #40: Divide check or numeric overflow.

## Example

for I=-1 to 1 step .1
print acs(I),
next
print "DONE"
end
->run
3.14 2.69 2.5 2.35 2.21 2.09 1.98 1.88 1.77 1.67 1.57 1.47 1.37 1.27 1.16 1.05 0.93 0.8 0.64 0.45 0 DONE