Locomotive BASIC - Polar Curves by Maurizio de Cesare

[ComSoft6128]

Type-in from the December 1988 issue of 'CPC Computing' magazine.
In this video I load five of the example files and then play about with the program by entering some unexpected values. 
The program is Listed at end of video.

Info from the magazine (with thanks to  CPCRulez)
"POLAR graphs form a continuous line around the origin - the point where X and Y axes cross. The mathematical function used to plot the shape is held in line 50, and this can be changed by altering everything after the - sign to one of those shown in Table I.

2*th 80*(COS(th)-0.5)
80*SIN(th) 40*(COS(2*th)-1)
80*COS(2*th) 50*(COS(2*th)-0.5 )
80 80*COS(3*th)
70+10*COS(6*th) 2*EXP(th/6.28)
70+10*COS(12*th) 70-40*SIN(2*th)
60+ 30*COS(6*th) 50-40*SIN(3*th)
60+30*RND(1) 50-40*SIN(th*th)
(Table I: Other polar functions)

When running the program you'll be asked to enter the number of divisions and multiples of Pi. For best results the divisions should be either 64 or 128. and the multiples either one, two, four or eight.
The variable rho is the distance from the current point on the curve to the origin, th is the angle between rho and the X axis. If all this sounds a bit dry, type it in and see the flower-like graphs the program generates."

Links:
https://cpcrulez.fr/applications_util-polar_curves_CCTG.htm
https://www.cpc-power.com/index.php?page=detail&num=17625
https://www.cpcwiki.eu/index.php/Computing_with_the_Amstrad

Not emulated - original hardware and software.
Please note that  the aspect ratio for this YouTube video is 16:9 but the CPC monitor
has an aspect ratio of 4:3 so you may wish to adjust your viewing device accordingly.