# HP Forums

Full Version: HP 41 Polar Plots?
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Anyone know if it's possible to plot f(r,theta) using an hp 41 and 82240 printer? For example:

R(theta) = 1/2 + 3/4*sin^2(theta) + 1/2*cos(theta)

describes the approximate plastic zone shape (normalized) ahead of a crack tip. Below is the solution in r, theta, x, y from 0< theta < 180 deg.

Code:
``` R            θ       x            y 1.00E+00    0       1.00E+00    0.00E+00 1.03E+00    15      9.98E-01    2.67E-01 1.12E+00    30      9.70E-01    5.60E-01 1.23E+00    45      8.69E-01    8.69E-01 1.31E+00    60      6.56E-01    1.14E+00 1.33E+00    75      3.44E-01    1.28E+00 1.25E+00    90      7.66E-17    1.25E+00 1.07E+00    105    -2.77E-01    1.03E+00 8.13E-01    120    -4.06E-01    7.04E-01 5.21E-01    135    -3.69E-01    3.69E-01 2.54E-01    150    -2.20E-01    1.27E-01 6.73E-02    165    -6.50E-02    1.74E-02 0.00E+00    180     0.00E+00    0.00E+00```

Ideally, you'd sort the x, y values to get the correct shape. I thought about writing a subroutine to do this using either "regplot" or "stkplot". Note there a two solutions at x = 0.
mbrethern

Someplace to start...

Polar Plot

...with an HP67-97 article/program from Electronics 1979

HP-67/97 program plots antenna's polar pattern

BEST!

SlideRule
If you're game for digging old software a few articles in PPC journal on related topics may help:

V10N6p23
V11N5p12
V11N7p10
V12N3p36
V13N5p20
V14N5p29
Reference URL's
• HP Forums: https://www.hpmuseum.org/forum/index.php
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