Add matfaust.rand_butterfly.

wrapper/matlab/+matfaust/rand_butterfly.m

+%====================================
+%> @brief Returns F, a random butterfly support Faust. Each factor is a butterfly factor.
+%>
+%> @param n: the power of two exponent, that is size(F, 2) == size(F, 1) == 2^n.
+%> @param 'dev', str: 'gpu or 'cpu' to create the Faust on CPU or GPU ('cpu' by default).
+%> @param 'field', str	str is either 'real' or 'complex' (the Faust field).
+%>                      The default value is 'real'.
+%> @param 'class', str 'double' (by default) or 'single' to select the scalar type used for the Faust generated.
+%>
+%> @retval F a random butterfly support Faust.
+%====================================
+function F = rand_butterfly(n, varargin)
+    import matfaust.dft
+	argc = length(varargin);
+	dev = 'cpu';
+	class = 'double';
+    field = 'real';
+	if(argc > 0)
+		for i=1:2:argc
+			if(argc > i)
+				% next arg (value corresponding to the key varargin{i})
+				tmparg = varargin{i+1};
+			end
+			switch(varargin{i})
+                case 'field'
+					if(argc == i || ~ strcmp(tmparg, 'real') && ~ strcmp(tmparg, 'complex'))
+						error('field keyword argument is not followed by a valid value: real, complex.')
+					else
+						field = tmparg;
+					end
+				case 'dev'
+					if(argc == i || ~ strcmp(tmparg, 'cpu') && ~ startsWith(tmparg, 'gpu'))
+						error('dev keyword argument is not followed by a valid value: cpu, gpu*.')
+					else
+						dev = tmparg;
+					end
+				case 'class'
+					if(argc == i || ~ strcmp(tmparg, 'double') && ~ strcmp(tmparg, 'single'))
+						error('class keyword argument is not followed by a valid value: single, double.')
+					else
+						class = tmparg;
+					end
+				otherwise
+					if((isstr(varargin{i}) || ischar(varargin{i}))  && ~ strcmp(tmparg, 'cpu') && ...
+                            ~ startsWith(tmparg, 'gpu') && ~ strcmp(tmparg, 'real') && ...
+                            ~ strcmp(tmparg, 'complex') && ~ strcmp(tmparg, 'single') && ~ strcmp(tmparg, 'double'))
+						error([ tmparg ' unrecognized argument'])
+					end
+			end
+        end
+    end
+    if strcmp(field, 'complex') && ~ strcmp(class, 'double')
+        error('if field is complex class must be double (complex single is not yet supported)')
+    end
+    DFT = dft(n);
+    % ignore the bitreversal permutation
+    B = factors(DFT, 1:numfactors(DFT)-1);
+    if n == 2
+        B = matfaust.Faust(B);
+    end
+    RB_factors = cell(1, numfactors(B));
+    for k=1:numfactors(B)
+        rb = factors(B, k);
+        if ~ strcmp(field, 'complex')
+            % real rb
+            rb = real(rb);
+            [I, J, ~] = find(rb);
+            for i=1:numel(I)
+                rb(I(i), J(i)) = randn(1);
+            end
+        else
+            % complex rb
+            [I, J, ~] = find(rb);
+            for i=1:numel(I)
+                rb(I(i), J(i)) = randn(1) + j * randn(1);
+            end
+        end
+        RB_factors{1, k} = rb;
+    end
+    F = matfaust.Faust(RB_factors);
+end