Merge pull request #1319 from Sonu0305/fix#865

Added the pol2cart functionality for Symbolic compatibility

INDEX

@@ -185,6 +185,7 @@ Mathematical methods for symbolic objects
  @sym/piecewise
  @sym/pinv
  @sym/pochhammer
+ @sym/pol2cart
  @sym/polylog
  @sym/potential
  @sym/prevprime

inst/@sym/cart2pol.m

@@ -66,7 +66,7 @@
 %% @end group
 %% @end example
 %%
-%% @seealso{cart2pol}
+%% @seealso{cart2pol, pol2cart}
 %% @end deftypemethod
 
 

inst/@sym/pol2cart.m

@@ -0,0 +1,160 @@
+%% Copyright (C) 2025 Swayam Shah
+%%
+%% This file is part of OctSymPy.
+%%
+%% OctSymPy is free software; you can redistribute it and/or modify
+%% it under the terms of the GNU General Public License as published
+%% by the Free Software Foundation; either version 3 of the License,
+%% or (at your option) any later version.
+%%
+%% This software is distributed in the hope that it will be useful,
+%% but WITHOUT ANY WARRANTY; without even the implied warranty
+%% of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+%% the GNU General Public License for more details.
+%%
+%% You should have received a copy of the GNU General Public
+%% License along with this software; see the file COPYING.
+%% If not, see <https://www.gnu.org/licenses/>.
+
+%% -*- texinfo -*-
+%% @documentencoding UTF-8
+%% @deftypemethod  @@sym {[@var{x}, @var{y}] =} pol2cart (@var{theta}, @var{r})
+%% @deftypemethodx @@sym {[@var{x}, @var{y}, @var{z}] =} pol2cart (@var{theta}, @var{r}, @var{z})
+%% @deftypemethodx @@sym {[@var{x}, @var{y}] =} pol2cart (@var{P})
+%% @deftypemethodx @@sym {[@var{x}, @var{y}, @var{z}] =} pol2cart (@var{P})
+%% Transform symbolic polar or cylindrical coordinates into Cartesian.
+%%
+%% If called with inputs @var{theta}, @var{r} (and @var{z}), they must be of the
+%% same shape or a scalar. The shape of the outputs @var{x}, @var{y} (and @var{z})
+%% matches those of the inputs (except when the input is a scalar).
+%%
+%% If called with a single input @var{P}, it must be a column vector with 2 or
+%% 3 entries, or a matrix with 2 or 3 columns. The column vector or each row
+%% of the matrix represents a point in polar or cylindrical coordinates
+%% (@var{theta}, @var{r}) or (@var{theta}, @var{r}, @var{z}). If input @var{P}
+%% is a column vector, outputs @var{x}, @var{y} (and @var{z}) are scalars.
+%% Otherwise, the shape of the outputs @var{x}, @var{y} (and @var{z}) is a
+%% column vector with each row corresponding to that of the input matrix @var{P}.
+%%
+%% Given a point (@var{theta}, @var{r}) in polar coordinates, its corresponding
+%% Cartesian coordinates can be obtained by:
+%% @example
+%% @group
+%% syms theta r real
+%% [x, y] = pol2cart (theta, r)
+%%   @result{} x = (sym) r⋅cos(θ)
+%%     y = (sym) r⋅sin(θ)
+%% @end group
+%% @end example
+%%
+%% Similarly, given a point (@var{theta}, @var{r}, @var{z}) in cylindrical
+%% coordinates, its corresponding Cartesian coordinates can be obtained by:
+%% @example
+%% @group
+%% syms theta r z real
+%% [x, y, z] = pol2cart (theta, r, z)
+%%   @result{} x = (sym) r⋅cos(θ)
+%%     y = (sym) r⋅sin(θ)
+%%     z = (sym) z
+%% @end group
+%% @end example
+%%
+%% @seealso{pol2cart, cart2pol}
+%% @end deftypemethod
+
+function [x, y, z_out] = pol2cart (theta_in, r_in, z_in)
+  %% obtain the kth column of matrix A
+  column_ref = @(A, k) subsref (A, substruct ('()', {':', k}));
+
+  if nargin == 1
+    P = sym (theta_in);
+    sz = size (P);
+    nrows = sz(1);
+    ncols = sz(2);
+    if isequal (sz, [2 1])
+      args = num2cell (P);
+      [x, y] = pol2cart (args{:});
+    elseif isequal (sz, [3 1])
+      args = num2cell (P);
+      [x, y, z_out] = pol2cart (args{:});
+    elseif ncols == 2
+      args = arrayfun (@(k) column_ref (P, k), 1:ncols, 'UniformOutput', false);
+      [x, y] = pol2cart (args{:});
+    elseif ncols == 3
+      args = arrayfun (@(k) column_ref (P, k), 1:ncols, 'UniformOutput', false);
+      [x, y, z_out] = pol2cart (args{:});
+    else
+      warning ('pol2cart: P must be a column vector with 2 or 3 entries, or a matrix with 2 or 3 columns');
+      print_usage ();
+    end
+    return
+  end
+
+  theta = sym (theta_in);
+  r = sym (r_in);
+  if isscalar (size (theta))
+    sz = size (r);
+  elseif isscalar (size (r)) || isequal (size (theta), size (r))
+    sz = size (theta);
+  else
+    error ('pol2cart: all inputs must have compatible sizes');
+  end
+  x = r .* cos (theta);
+  y = r .* sin (theta);
+
+  if nargin == 3
+    z = sym (z_in);
+    if isscalar (z)
+      z_out = z * ones (sz);
+    elseif isequal(size (z), sz)
+      z_out = z;
+    else
+      error ('pol2cart: all inputs must have compatible sizes');
+    end
+  end
+end
+
+
+%!test
+%! % multiple non-scalar inputs
+%! theta = sym ('theta', [2 2]);
+%! assume (theta, 'real');
+%! r = sym ('r', [2 2]);
+%! assume (r, 'real');
+%! [x, y] = pol2cart (theta, r);
+%! assert (isequal (x, r .* cos (theta)));
+%! assert (isequal (y, r .* sin (theta)));
+%! % mixing scalar inputs with non-scalar inputs
+%! syms z real
+%! [x_2, y_2, z_2] = pol2cart (theta, r, z);
+%! assert (isequal (x_2, r .* cos (theta)));
+%! assert (isequal (y_2, r .* sin (theta)));
+%! assert (isequal (z_2, z * ones (2, 2)));
+
+%!test
+%! % column vector with 2 entries
+%! syms theta r real
+%! [x, y] = pol2cart ([theta; r]);
+%! assert (isequal (x, r * cos (theta)));
+%! assert (isequal (y, r * sin (theta)));
+%! % column vector with 3 entries
+%! syms z real
+%! [x_2, y_2, z_2] = pol2cart ([theta; r; z]);
+%! assert (isequal (x_2, r * cos (theta)));
+%! assert (isequal (y_2, r * sin (theta)));
+%! assert (isequal (z_2, z));
+
+%!test
+%! % matrix with 2 columns
+%! syms theta r u v real
+%! P = [theta r; u v];
+%! [x, y] = pol2cart (P);
+%! assert (isequal (x, [r * cos(theta); v * cos(u)]));
+%! assert (isequal (y, [r * sin(theta); v * sin(u)]));
+%! % matrix with 3 columns
+%! syms z w real
+%! P_2 = [theta r z; u v w];
+%! [x_2, y_2, z_2] = pol2cart (P_2);
+%! assert (isequal (x_2, [r * cos(theta); v * cos(u)]));
+%! assert (isequal (y_2, [r * sin(theta); v * sin(u)]));
+%! assert (isequal (z_2, [z; w]));