Hi, Thank you for the example re: polyshape , square wave. I am surprised to see that fractions vs. decimals for amps in the float-vector makes a difference in the chebyshev coefficients.
(partials->polynomial (float-vector 1 1 3 1/3 5 1/5 7 1/7 9 1/9 )) ;(0.0 1.0 0.0 -7.999999999999999 0.0 35.2 0.0 -54.85714285714286 0.0 28.44444444444444) (with-sound (:srate 48000 :channels 1 :play #t) (let ((gen (make-polyshape 100.0 :coeffs #r(0.0 1.0 0.0 -7.999999999999999 0.0 35.2 0.0 -54.85714285714286 0.0 28.44444444444444) )) ) (do ((i 0 (+ i 1))) ((= i 88200)) (outa i (* .75 (polyshape gen 1.0 )))))) When trying to plug the coefficents back into make-polyshape, I get a different wave shape, which looks more like a triangle-ish wave instead of the square: ^^^^^^ I believe this is where I'm stuck, trying to empirically understand how the chebyshev coefficient numbers work for additive synthesis. I thought the problem might be normalization or order of coefficients? Still not sure where I'm going wrong. Any help, advice much appreciated. Regards, Jim ________________________________ From: cmdist-boun...@ccrma.stanford.edu <cmdist-boun...@ccrma.stanford.edu> on behalf of cmdist-requ...@ccrma.stanford.edu <cmdist-requ...@ccrma.stanford.edu> Sent: Tuesday, October 26, 2021 9:00 AM To: cmdist@ccrma.Stanford.EDU <cmdist@ccrma.Stanford.EDU> Subject: Cmdist Digest, Vol 161, Issue 11 Send Cmdist mailing list submissions to cmdist@ccrma.stanford.edu To subscribe or unsubscribe via the World Wide Web, visit https://cm-mail.stanford.edu/mailman/listinfo/cmdist or, via email, send a message with subject or body 'help' to cmdist-requ...@ccrma.stanford.edu You can reach the person managing the list at cmdist-ow...@ccrma.stanford.edu When replying, please edit your Subject line so it is more specific than "Re: Contents of Cmdist digest..." Today's Topics: 1. poly questions (James Hearon) ---------------------------------------------------------------------- Message: 1 Date: Tue, 26 Oct 2021 17:40:43 +0000 From: James Hearon <j_hea...@hotmail.com> To: "cmdist@ccrma.Stanford.EDU" <cmdist@ccrma.Stanford.EDU> Subject: [CM] poly questions Message-ID: <dm6pr10mb2537ab5eb7d8ec958cbb12c2e5...@dm6pr10mb2537.namprd10.prod.outlook.com> Content-Type: text/plain; charset="iso-8859-1" Hi, Trying to get an understanding of all the interesting aspects of polywave in snd, and chebyshev polynomials, coefficients etc. I was trying to get a squarish wave from the coefficients but failing. Also tried partials->polynomial, and normalize-partials with same result. Wondering what I'm misunderstanding about how you would employ the coefficients for a typical float-vector of partials, and amps for say a square wave? (with-sound (:srate 48000 :channels 1 :play #t) (let ((gen (make-polyshape 100.0 :coeffs (partials->polynomial (float-vector 1 1 3 .33 5 .2 7 .142 9 0.111)) )) ) (do ((i 0 (+ i 1))) ((= i 88200)) (outa i (* .75 (polyshape gen 1.0 )))))) Also, if I can ask more than one question per email, how do you go about using the generators: mus-chebyshev-tu-sum x t-coeffs u-coeffs mus-chebyshev-t-sum x t-coeffs mus-chebyshev-u-sum x u-coeffs I couldn't seem to locate an ex. for those, but I did see the c code in clm.c which is interesting. Thank you, Regards, Jim -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://cm-mail.stanford.edu/pipermail/cmdist/attachments/20211026/e9ebab85/attachment-0001.html> ------------------------------ _______________________________________________ Cmdist mailing list Cmdist@ccrma.stanford.edu https://cm-mail.stanford.edu/mailman/listinfo/cmdist End of Cmdist Digest, Vol 161, Issue 11 ***************************************
_______________________________________________ Cmdist mailing list Cmdist@ccrma.stanford.edu https://cm-mail.stanford.edu/mailman/listinfo/cmdist