Implement filter2.sci in Scilab

1 files changed, 65 insertions, 28 deletions

diff --git a/macros/filter2.sci b/macros/filter2.sci
index b8b48e4..f565e14 100644
--- a/macros/filter2.sci
+++ b/macros/filter2.sci
@@ -1,33 +1,70 @@
-function Y = filter2 (B, X, SHAPE)
-//Apply the 2-D FIR filter B to X.
-//Calling Sequence
-//Y = filter2(B, X)
-//Y = filter2(B, X, SHAPE)
-//Parameters
-//B, X: Matrix  
-// SHAPE: 
-//        'full':  pad X with zeros on all sides before filtering.
-//        'same': unpadded X (default)
-//        'valid': trim X after filtering so edge effects are no included. 
-//Description
-//This function applies the 2-D FIR filter B to X. If the argument SHAPE is specified, return an array of the desired shape.
-//Examples
+function y = filter2 (b, x, shape)
+//Apply the 2-D FIR filter b to x.
+//Calling Sequence:
+//y =  filter2(b, x)
+//y = filter2(b, x, shape)
+//Parameters:
+//b, x: vectors
+//If the optional argument 'shape' is specified, return a vector of the desired shape. 
+//Possible values are:
+//  "full"- pad x with zeros on all sides before filtering.
+//  "same"- unpadded x (default)
+//  "valid"- trim x after filtering so edge effects are no included.
+//Examples:
 //filter2([1,3], [4,5])
-//ans = 
-//     19.    5.  
-funcprot(0);
-lhs = argn(1)
-rhs = argn(2)
-if (rhs < 2 | rhs > 3)
-error("Wrong number of input arguments.")
-end
+//ans =
+//[19, 5]
 
-select(rhs)
-	
-	case 2 then
-        Y=callOctave("filter2",B,X)
-	case 3 then
-		Y = callOctave("filter2",B,X,SHAPE)
+  funcprot(0);
+  rhs = argn(2);
+
+  if (rhs < 2 | rhs > 3) then
+    error("filter2: wrong number of input arguments");
+  end
+  if (rhs < 3) then
+    shape = "same";
+  end
+ [nr, nc] = size(b);
+  A = x;
+  B = b(nr:-1:1, nc:-1:1);
+  fullConv = convol2d(A, B);
+  sizeA = size(A);
+  sizeB = size(B);
+  sizeFull = size(fullConv);
+
+  select(shape)
+    case "full"
+      y = fullConv;
+    case "same"
+      startRow = floor(sizeB(1) / 2) + 1;
+      startCol = floor(sizeB(2) / 2) + 1;
+      endRow = startRow + sizeA(1) - 1;
+      endCol = startCol + sizeA(2) - 1;
+      y = fullConv(startRow:endRow, startCol:endCol);
+    case "valid"
+      startRow = sizeB(1);
+      startCol = sizeB(2);
+      endRow = sizeFull(1) - sizeB(1) + 1;
+      endCol = sizeFull(2) - sizeB(2) + 1;
+      if endRow >= startRow & endCol >= startCol then
+          y = fullConv(startRow:endRow, startCol:endCol);
+      else
+          y = [];
+      end
+    else
+        error("Invalid shape parameter.");
     end
 
 endfunction
+
+//input validation:
+//assert_checkerror("filter2()", "filter2: wrong number of input arguments");
+//assert_checkerror("filter2(1, 2, 3, 4)", "Wrong number of input arguments.");
+
+//tests:
+//assert_checkequal(filter2([1, 2; 3, 5], [1, 3; 5, 7]), [57, 24; 19, 7]);
+//assert_checkequal(filter2(1, 5), filter2(1, 5, "same"));
+//assert_checkequal(filter2([1, 2], [4; 5; 6], "full"), [8, 4; 10, 5; 12, 6]);
+//assert_checkequal(filter2([3; 1], [5; 4], "valid"), 19);
+//x=1;
+//assert_checkequal(filter2([3 x*2; 3*x+1 9^x], [5 7; 4 8], "valid"), 117);