X-Git-Url: https://scm.cri.ensmp.fr/git/Faustine.git/blobdiff_plain/c7f552fd8888da2f0d8cfb228fe0f28d3df3a12c..b4b6f2ea75b9f0f3ca918f5b84016610bf7a4d4f:/interpretor/preprocessor/faust-0.9.47mr3/examples/rewriting/sum.dsp

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+
+// How to emulate Faust's seq, par, sum.
+// x(k) is assumed to yield the kth signal.
+
+xseq(1,x)	= x(0);
+xseq(n,x)	= xseq(n-1,x) : x(n-1);
+
+xpar(1,x)	= x(0);
+xpar(n,x)	= xpar(n-1,x) , x(n-1);
+
+xsum(1,x)	= x(0);
+xsum(n,x)	= xsum(n-1,x) + x(n-1);
+
+// These are all very similar. Abstracting
+// on the binary "accumulator" function, we
+// get the familiar fold(-left) function:
+
+fold(1,f,x)	= x(0);
+fold(n,f,x)	= f(fold(n-1,f,x),x(n-1));
+
+// Now seq, par, sum can be defined as:
+
+fseq(n)		= fold(n,\(x,y).(x:y));
+fpar(n)		= fold(n,\(x,y).(x,y));
+fsum(n)		= fold(n,+);
+
+// Often it is more convenient to specify
+// parameters as a Faust tuple. We can match
+// against the (x,y) pattern to decompose
+// these.
+
+vfold(f,(x,y))	= f(vfold(f,x),y);
+vfold(f,x)	= x;
+
+// Tuple version of seq, par, sum:
+
+vseq		= vfold(\(x,y).(x:y));
+vpar		= vfold(\(x,y).(x,y));
+vsum		= vfold(+);
+
+// Example: sum of sinusoids.
+
+import("music.lib");
+
+f0		= 440;
+a(0)		= 1;
+a(1)		= 0.5;
+a(2)		= 0.3;
+h(i)		= a(i)*osc((i+1)*f0);
+
+v		= hslider("vol", 0.3, 0, 1, 0.01);
+
+process		= v*fsum(3,h);
+//process	= v*xsum(3,h);
+//process	= v*vsum((h(0),h(1),h(2)));