I work in graphics and seem to lately be referring to these articles more than papers. I love how playful IQ’s investigations are, as well as how practical and useful.<p>Recently I tried writing a sound program on ShaderToy and without thinking much assumed you could easily vary the frequency of a tone by using sin( t * freq * tau ) and animating freq. Whoo my ears got a big surprise, and a Google search brought me right to <a href="https://www.iquilezles.org/www/articles/fm/fm.htm" rel="nofollow">https://www.iquilezles.org/www/articles/fm/fm.htm</a>