1 files changed, 80 insertions, 0 deletions
diff --git a/pd/doc/3.audio.examples/buttercoef3.pd b/pd/doc/3.audio.examples/buttercoef3.pd
new file mode 100644
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+++ b/pd/doc/3.audio.examples/buttercoef3.pd
@@ -0,0 +1,80 @@
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+#X obj 63 51 inlet;
+#X floatatom 522 134 5 0 0 0 - - -;
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+#X msg 101 108 0.667;
+#X msg 82 283 0;
+#X obj 517 270 loadbang;
+#X obj 528 298 inlet;
+#X obj 517 322 f;
+#X obj 517 346 expr 1 - 2*$f1;
+#X obj 63 79 t b b b f;
+#X obj 205 228 * -1;
+#X obj 163 228 t f f;
+#X obj 63 391 f;
+#X obj 30 463 outlet;
+#X text 515 237 1 to normalize at Nyquist;
+#X text 59 30 characteristic frequency \, 0(DC) to 1(Nyquist);
+#X obj 283 470 outlet;
+#X obj 439 472 outlet;
+#X text 439 494 imag2a;
+#X text 283 492 real1;
+#X text 374 494 real2;
+#X obj 500 473 outlet;
+#X text 500 495 imag2b;
+#X obj 373 470 outlet;
+#X text 27 485 normalizer1;
+#X obj 173 470 outlet;
+#X text 170 492 normalizer2;
+#X obj 156 436 expr (($f2-$f1)*($f2-$f1)+$f3*$f3);
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+#X obj 101 176 expr (1 - $f2*$f2) / (1 + $f2*$f2 + 2*$f2*cos($f1))
+;
+#X obj 163 205 expr 2*$f2*sin($f1) / (1 + $f2*$f2 + 2*$f2*cos($f1))
+;
+#X obj 82 307 expr (1 - $f2*$f2) / (1 + $f2*$f2 + 2*$f2*cos($f1));
+#X obj 522 89 clip 0 1;
+#X obj 522 111 expr tan($f1*1.57);
+#X obj 101 131 expr $f1*1.5708;
+#X text 515 251 0 to normalize at DC;
+#X text 119 4 3-pole (or zero) Butterworth filter coefficient calculator
+;
+#X text 145 109 "theta" in units of pi/2;
+#X text 211 138 conjugate pair of pole/zero locations:;
+#X text 197 155 real part: (1-r*r)/(1+r*r-2rcos(th));
+#X text 245 226 imaginary part: 2rsin(th)/(...);
+#X text 270 282 real-valued one \, theta=0;
+#X obj 30 439 expr abs($f1-$f2);
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