Richard Ashbery has added another section to his website on the subject of simple graphics programming in BBC BASIC V on RISC OS. Section 8 (which sounds ominously like some top secret government black ops outfit until you discover that it…) covers parametric (not paramilitary) equations. Ahem. Anyway…
According to Richard, these equations can be used to draw standard geometric shapes such as circles, squares, triangles, etc., along with more intricate patterns such as astroids, rose patterns, fish curves, hypo-cycloids, etc. There are twelve example graphic illustrations included at the end of the section.