commands → arctan

arctan(x)

The arctan command computes the inverse tangent of x where x is in radians. If x is a floating point number then a floating point result is computed, otherwise the result is an exact symbolic value.

Examples 

# hardware floating point
arctan(1.0);
	0.785398163397448

# symbolic
arctan(1);
	arctan(1)

Algorithm

To compute arctan(x) in extended precision, we compute Newton's accelerated power series.

References

Accelerated Arctangent Series on Wikipedia
Gullberg, Jan. Mathematics: From the Birth of Numbers. Norton, 1996.