$ZTAN returns the trigonometric tangent of n. The result is a signed decimal number.
Note:
$ZTAN (like all trigonometric functions) calculates its values based on pi rounded to the number of available decimal digits. Therefore, the value returned by $ZTAN($ZPI) is –.000000000000000000462644 and $ZTAN(–$ZPI) is .000000000000000000462644. For this reason you should not perform limit tests comparing these returned values to 0. $ZTAN(0) is 0.
The following example permits you to compute the tangent of a number:
READ"Input a number: ",numWRITE!,"the tangent is: ",$ZTAN(num)QUIT
The following example compares the results from InterSystems IRIS fractional numbers ($DECIMAL numbers) and $DOUBLE numbers. In both cases, the tangent of 0 is exactly 0, but the tangent of pi is a negative fractional number (not exactly 0):
WRITE!,"the tangent is: ",$ZTAN(0.0)WRITE!,"the tangent is: ",$ZTAN($DOUBLE(0.0))WRITE!,"the tangent is: ",$ZTAN($ZPI)WRITE!,"the tangent is: ",$ZTAN($DOUBLE($ZPI))WRITE!,"the tangent is: ",$ZTAN(1.0)WRITE!,"the tangent is: ",$ZTAN($DOUBLE(1.0))