$ZARCCOS
Inverse (arc) cosine function.
Synopsis
$ZARCCOS(n)
Parameter
| Argument | Description |
|---|---|
| n | A signed decimal number. |
Description
$ZARCCOS returns the trigonometric inverse (arc) cosine of n. The result is given in radians (to 18 decimal places).
Parameter
n
Signed decimal number ranging from 1 to -1 (inclusive). It can be specified as a value, a variable, or an expression. Numbers outside the range generate an <ILLEGAL VALUE> error. A non-numeric string is evaluated as 0.
The following are arc cosine values returned by $ZARCCOS:
| 1 | returns 0 |
| 0 | returns 1.570796326794896619 |
| -1 | returns pi (3.141592653589793238) |
Examples
The following example permits you to compare the arc cosine and the arc sine of a number:
READ "Input a number: ",num
IF num>1 { WRITE !,"ILLEGAL VALUE: number too big" }
ELSEIF num<-1 { WRITE !,"ILLEGAL VALUE: number too small" }
ELSE {
WRITE !,"the arc cosine is: ",$ZARCCOS(num)
WRITE !,"the arc sine is: ",$ZARCSIN(num)
}
QUITThe following example compares the results from Caché fractional numbers ($DECIMAL numbers) and $DOUBLE numbers. In both cases, the arc cosine of 1 is exactly 0:
WRITE !,"the arc cosine is: ",$ZARCCOS(0.0)
WRITE !,"the arc cosine is: ",$ZARCCOS($DOUBLE(0.0))
WRITE !,"the arc cosine is: ",$ZARCCOS(1.0)
WRITE !,"the arc cosine is: ",$ZARCCOS($DOUBLE(1.0))
WRITE !,"the arc cosine is: ",$ZARCCOS(-1.0)
WRITE !,"the arc cosine is: ",$ZARCCOS($DOUBLE(-1.0))
