WP-34S Polar to Rectangular (no quadrant checking)

[BarryMead]

Many HP calculators include special quadrant checking for the 0, 90, 180, 270 degree quadrant values when performing the Polar to Rectangular conversion. For instance if you have 90 degrees in the
Y register and 1 in the X register and press "f" "R<" (Polar to Rectangular) you get 3.799 E -38 for X and 1 for Y on the WP-34s (assuming Degrees mode), but on an HP-15C you get 0 (zero) for X and 1 for Y.
If the calculator were in GRADS mode these values would be 0, 100, 200, 300. Most HP calculators don't attempt to match quadrant angular values while in the RAD mode.

Adding special checks for these quadrant values could cost valuable flash memory space, but since the existing SIN and COS functions already include these special quadrant checks, it may be possible to fix the Polar to Rectangular function by using existing SIN and COS routines, hopefully eliminating the need for additional quadrant checks.