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--- tutorial_subsystem [2014/07/12 07:00]
guillaume Part 1 posted
+++ tutorial_subsystem [2017/04/19 13:31]
@@ Line 1: / Line 1: @@
-======SubSystem in Alpha======
-In this tutorial, we will present how to write structured alpha programs with subsystems, and we will present the associated transformations.
-====Syntax of Use Equation (without extension domain)====
-Let us assume that we want to compute the mean of the values of a vector. It is feasible through the following Alpha system:
-<sxh alphabets; gutter:false>
-affine mean {N | N>0}
-input
-	float A {k | 0<=k<N};
-output
-	float C {|};
-local
-	float temp {|};
-let
-	temp = reduce(+, [k], A[k]);
-	C = temp / N;
-.
-</sxh>
-However, let us assume that you already have another Alpha system which computes the sum of the elements of a vector. It is possible to use this affine system (instead of rewriting its equation in the main system), by calling it through a "use equation":
-<sxh alphabets; gutter:false>
-affine sum {P| P>0}	// Computes the sum of the elements of a vector of size P
-input
-	float vect {i | 0<=i<P };
-output
-	float Res;
-let
-	Res = reduce(+, [k], vect[k]);
-.
-affine mean {N | N>0}
-input
-	float A {k | 0<=k<N};
-output
-	float C {|};
-local
-	float temp {|};
-let
-	use sum[N] (A) returns (temp);		// Compute "temp" using the system "sum"
-	C = temp / N;
-.
-</sxh>
-The system "mean" is calling the system "sum" (which is called a subsystem). The subsystem is called with the parameter "N" and the input "A". After doing its computation, the result of "sum" will be stored inside the local variable "temp".
-In general, the syntax of a use equation is the following:
-<sxh alphabets; gutter:false>
-use subsystem_name[list of parameters] (list of input expressions) returns (list of output variables);
-</sxh>
-If your subsystem have several parameters/inputs/outputs, you have to provide them in the order in which they are declared.
-====Extension domain====
-(incoming)
-====Transformations involving subsystems====
-(incoming, after the previous incoming)

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