Still playing with these but some help would help
also why can you use
0j1p1
0j3.14159
but not
o.1
3.14159
0jo.1
|ill-formed number
Donna
[EMAIL PROTECTED]
On 30-Jun-06, at 1:05 AM, Henry Rich wrote:
More than one post in this thread has conflated 1r_1 with 1j_1
and I wonder if everyone who is interested (which doesn't
include me) is getting the right meaning out of it.
Henry Rich
Eldon's point, and my code on arctan _1r1, were concerned with
variant
defintions of arctan. Arctan is normally defined by restricting the
domain of tangent to the open interval (-1r2p1, 1r2p1), so it
always gives
an angle in the first or fourth quadrant. In many
applications, you want
the angle from the x-axis to the point (x,y), which can be in any
quadrant. This is basically arctan y%x, except it takes sign into
account. Library functions called atan2 usually do this, and
J does it
via angle (12&o.). Then arctan _1 is _1r4p1 (in the fourth
quadrant),
same as the angle to (1,_1), but different from the angle to (_1,1).
Best wishes,
John
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