Merge pull request #233 from RonaldoCMP/master

Minor changes in arrays.scad and math.scad

arrays.scad

@@ -1287,6 +1287,10 @@ function array_dim(v, depth=undef) =
 
 // Function: transpose()
 // Description: Returns the transposition of the given array.
+//    When reverse=true, the transposition is done in respect to the secondary diagonal, that is:
+//    .
+//    reverse(transpose(reverse(arr))) == transpose(arr, reverse=true)
+//    By default, reverse=false.
 // Example:
 //   arr = [
 //       ["a", "b", "c"],
@@ -1313,14 +1317,30 @@ function array_dim(v, depth=undef) =
 //   //     ["c", "f"],
 //   // ]
 // Example:
+//   arr = [
+//       ["a", "b", "c"],
+//       ["d", "e", "f"],
+//       ["g", "h", "i"]
+//   ];
+//   t = transpose(arr, reverse=true);
+//   // Returns:
+//   // [
+//   //  ["i", "f", "c"],
+//   //  ["h", "e", "b"],
+//   //  ["g", "d", "a"]
+//   // ]
+// Example:
 //   transpose([3,4,5]);  // Returns: [3,4,5]
-function transpose(arr) =
+function transpose(arr, reverse=false) =
     assert( is_list(arr) && len(arr)>0, "The array is not a vector neither a matrix." )
     is_list(arr[0])
     ?   let( l0 = len(arr[0]) )
         assert([for(a=arr) if(!is_list(a) || len(a)!=l0) 1 ]==[], "The array is not a vector neither a matrix." )
-        [for (i=[0:1:l0-1]) 
-            [ for (j=[0:1:len(arr)-1]) arr[j][i] ] ] 
+        reverse
+        ? [for (i=[0:1:l0-1]) 
+              [ for (j=[0:1:len(arr)-1]) arr[len(arr)-1-j][l0-1-i] ] ] 
+        : [for (i=[0:1:l0-1]) 
+              [ for (j=[0:1:len(arr)-1]) arr[j][i] ] ] 
     :  assert( is_vector(arr), "The array is not a vector neither a matrix." )
            arr;
 

math.scad

@@ -698,9 +698,8 @@ function linear_solve(A,b) =
     zeros != [] ? [] :
     m<n 
     // avoiding input validation in back_substitute
-    ? let( n  = len(R),
-           Rt = [for(i=[0:n-1]) [for(j=[0:n-1]) R[n-1-j][n-1-i]]] )
-      Q*reverse(_back_substitute(Rt,reverse(b))) 
+    ? let( n  = len(R) )
+      Q*reverse(_back_substitute(transpose(R, reverse=true), reverse(b))) 
     : _back_substitute(R, transpose(Q)*b);
 
 // Function: matrix_inverse()
@@ -728,13 +727,14 @@ function qr_factor(A) =
       n = len(A[0])
     )
     let(
-        qr =_qr_factor(A, column=0, m = m, n=n, Q=ident(m)),
-        Rzero = [
-            for(i=[0:m-1]) [
-                for(j=[0:n-1])
-                i>j ? 0 : qr[1][i][j]
+        qr =_qr_factor(A, Q=ident(m), column=0, m = m, n=n),
+        Rzero = 
+          let( R = qr[1] )
+          [ for(i=[0:m-1]) [
+              let( ri = R[i] )
+              for(j=[0:n-1]) i>j ? 0 : ri[j]
             ]
-        ]
+          ]
     ) [qr[0],Rzero];
 
 function _qr_factor(A,Q, column, m, n) =
@@ -763,13 +763,12 @@ function back_substitute(R, b, transpose = false) =
     let(n=len(R))
     assert(is_vector(b,n) || is_matrix(b,n),str("R and b are not compatible in back_substitute ",n, len(b)))
     transpose
-      ? reverse(_back_substitute([for(i=[0:n-1]) [for(j=[0:n-1]) R[n-1-j][n-1-i]]],
-                                 reverse(b)))  
+      ? reverse(_back_substitute(transpose(R, reverse=true), reverse(b)))  
       : _back_substitute(R,b);
 
 function _back_substitute(R, b, x=[]) =
-      let(n=len(R))
-      len(x) == n ? x
+    let(n=len(R))
+    len(x) == n ? x
     : let(ind = n - len(x) - 1)
       R[ind][ind] == 0 ? []
     : let(

paths.scad

@@ -43,10 +43,12 @@ include <triangulation.scad>
 //   dim = list of allowed dimensions of the vectors in the path.  Default: [2,3]
 //   fast = set to true for fast check that only looks at first entry.  Default: false
 function is_path(list, dim=[2,3], fast=false) =
-    fast? is_list(list) && is_vector(list[0]) :
-    is_list(list) && is_list(list[0]) && len(list)>1 &&
-    (is_undef(dim) || in_list(len(list[0]), force_list(dim))) &&
-    is_list_of(list, repeat(0,len(list[0])));
+    fast
+    ?   is_list(list) && is_vector(list[0]) 
+    :   is_matrix(list) 
+        && len(list)>1 
+        && len(list[0])>0
+        && (is_undef(dim) || in_list(len(list[0]), force_list(dim)));
 
 
 // Function: is_closed_path()
@@ -105,32 +107,51 @@ function path_subselect(path, s1, u1, s2, u2, closed=false) =
 
 // Function: simplify_path()
 // Description:
-//   Takes a path and removes unnecessary collinear points.
+//   Takes a path and removes unnecessary subsequent collinear points.
 // Usage:
 //   simplify_path(path, [eps])
 // Arguments:
-//   path = A list of 2D path points.
+//   path = A list of path points of any dimension.
 //   eps = Largest positional variance allowed.  Default: `EPSILON` (1-e9)
 function simplify_path(path, eps=EPSILON) =
-    len(path)<=2? path : let(
-        indices = concat([0], [for (i=[1:1:len(path)-2]) if (!collinear_indexed(path, i-1, i, i+1, eps=eps)) i], [len(path)-1])
-    ) [for (i = indices) path[i]];
+    assert( is_path(path), "Invalid path." )
+    assert( is_undef(eps) || (is_finite(eps) && (eps>=0) ), "Invalid tolerance." )    
+    len(path)<=2 ? path 
+    :   let(
+            indices = [ 0,
+                        for (i=[1:1:len(path)-2]) 
+                            if (!collinear(path[i-1],path[i],path[i+1], eps=eps)) i, 
+                        len(path)-1 
+                      ]
+        ) 
+        [for (i = indices) path[i] ];
 
 
 // Function: simplify_path_indexed()
 // Description:
-//   Takes a list of points, and a path as a list of indices into `points`,
-//   and removes all path points that are unecessarily collinear.
+//   Takes a list of points, and a list of indices into `points`,
+//   and removes from the list all indices of subsequent indexed points that are unecessarily collinear.
+//   Returns the list of the remained indices.
 // Usage:
-//   simplify_path_indexed(path, eps)
+//   simplify_path_indexed(points,indices, eps)
 // Arguments:
 //   points = A list of points.
-//   path = A list of indices into `points` that forms a path.
+//   indices = A list of indices into `points` that forms a path.
 //   eps = Largest angle variance allowed.  Default: EPSILON (1-e9) degrees.
-function simplify_path_indexed(points, path, eps=EPSILON) =
-    len(path)<=2? path : let(
-        indices = concat([0], [for (i=[1:1:len(path)-2]) if (!collinear_indexed(points, path[i-1], path[i], path[i+1], eps=eps)) i], [len(path)-1])
-    ) [for (i = indices) path[i]];
+function simplify_path_indexed(points, indices, eps=EPSILON) =
+    len(indices)<=2? indices 
+    : let(
+        indices = concat( indices[0], 
+                          [for (i=[1:1:len(indices)-2]) 
+                              let( 
+                                  i1 = indices[i-1],
+                                  i2 = indices[i],
+                                  i3 = indices[i+1]
+                              )
+                              if (!collinear(points[i1],points[i2],points[i3], eps=eps)) indices[i]], 
+                          indices[len(indices)-1] )
+        ) 
+        indices;
 
 
 // Function: path_length()

tests/test_arrays.scad

@@ -480,6 +480,7 @@ test_array_dim();
 module test_transpose() {
     assert(transpose([[1,2,3],[4,5,6],[7,8,9]]) == [[1,4,7],[2,5,8],[3,6,9]]);
     assert(transpose([[1,2,3],[4,5,6]]) == [[1,4],[2,5],[3,6]]);
+    assert(transpose([[1,2,3],[4,5,6]],reverse=true) == [[6,3], [5,2], [4,1]]);
     assert(transpose([3,4,5]) == [3,4,5]);
 }
 test_transpose();