clean up a bit

@chebfun2v/coeffs2.m

@@ -11,6 +11,12 @@
 % Copyright 2019 by The University of Oxford and The Chebfun Developers.
 % See http://www.chebfun.org/ for Chebfun information.
 
+
+if isempty(f)
+    varargout = {}; 
+    return
+end
+
 F1 = f.components{1};
 F2 = f.components{2}; 
 if isempty(varargin)

@chebfun2v/coeffs2vals.m

@@ -2,7 +2,7 @@
 % COEFFS2VALS  componentwise conversion of matrix of bivariate Chebyshev
 % coefficients to values.
 %
-%  X,Y = COEFFS2VALS( U, V ) converts matrices U and V of bivariate
+%  X,Y = COEFFS2VALS(U, V) converts matrices U and V of bivariate
 %  Chebyshev coefficients to matrices of samples X and Y corresponding 
 % to values sampled on a 2D tensor Chebyshev grid. 
 %

@chebfun2v/vals2coeffs.m

@@ -1,4 +1,4 @@
-function [X, Y] = vals2coeffs(U,V)
+function [U, V] = vals2coeffs(X,Y)
 % VALS2COEFFS  componentwise conversion of matrices of values to
 % matrices of bivariate Chebyshev coefficients.
 %
@@ -12,12 +12,8 @@
 % Copyright 2019 by The University of Oxford and The Chebfun Developers.
 % See http://www.chebfun.org/ for Chebfun information. 
 
-%%
-% Empty check:
-
-
-X = chebfun2.vals2coeffs(U); 
-Y = chebfun2.vals2coeffs(V); 
+U = chebfun2.vals2coeffs(X); 
+V = chebfun2.vals2coeffs(Y); 
 end
 
 

@diskfun/coeffs2.m

@@ -15,6 +15,14 @@
 % Copyright 2017 by The University of Oxford and The Chebfun Developers.
 % See http://www.chebfun.org/ for Chebfun information.
 
+
+
+%empty check
+if isempty(f)
+    varargout = {}; 
+    return
+end
+
 % Calculate the CDR decomposition: 
 [C, D, R] = cdr( f ); 
 

@diskfun/coeffs2diskfun.m

@@ -2,7 +2,7 @@
 %COEFFS2DISKFUN   Convert a matrix of Chebyshev-Fourier coefficients to a 
 %                 diskfun. 
 % 
-%   F = coeffs2diskfun(X) returns a diskfun object F that has a
+%   F = coeffs2diskfun( X ) returns a diskfun object F that has a
 %   Chebyshev-Fourier matrix of coefficients X.  This is useful for
 %   computing quantities on the disk with the function F.
 % 

@diskfun/coeffs2vals.m

@@ -11,7 +11,6 @@
 % low rank form. Here, C*D*R.' is a 2D coeff matrix.
 %
 
-% 
 % See also VALS2COEFFS.
 
 % Copyright 2019 by The University of Oxford and The Chebfun Developers.

@diskfun/vals2coeffs.m

@@ -1,7 +1,7 @@
-function varargout = vals2coeffs( U, varargin)
+function varargout = vals2coeffs( U, varargin )
 %VALS2COEFFS    Convert matrix of values to Chebyshev-Fourier coefficients. 
 % 
-% V = VALS2COEFFS( C ) converts a matrix C of values representing 
+% V = VALS2COEFFS( U ) converts a matrix U of values representing 
 % samples of a function from a tensor Chebyshev-Fourier grid 
 % to a matrix V of Chebyshev-Fourier coefficients for the corresponding 
 % interpolant.
@@ -24,7 +24,7 @@
     V = varargin{2}; 
     U = chebtech2.vals2coeffs( U ); 
     V = trigtech.vals2coeffs( V );     
-    varargout = {U S V};
+    varargout = { U S V };
 else
     error('CHEBFUN:DISKFUN:vals2coeffs:inputs', ...
         'The number of input arguments should be one or two.');

@diskfunv/coeffs2.m

@@ -13,6 +13,13 @@
 % Copyright 2017 by The University of Oxford and The Chebfun Developers.
 % See http://www.chebfun.org/ for Chebfun information.
 
+
+%empty check
+if isempty(f)
+    varargout = {}; 
+    return
+end
+
 F1 = f.components{1};
 F2 = f.components{2}; 
 if isempty(varargin)

@diskfunv/coeffs2diskfunv.m

@@ -1,8 +1,8 @@
-function F = coeffs2diskfunv(X, Y)
+function F = coeffs2diskfunv( X, Y )
 %COEFFS2DISKFUNV   Convert componentwise matrices of Chebyshev-Fourier 
 %   coefficients to a diskfunv. 
 % 
-%   F = coeffs2diskfunv(X, Y) returns a diskfunv object F that has a
+%   F = coeffs2diskfunv( X, Y ) returns a diskfunv object F that has a
 %   Chebyshev-Fourier matrices of coefficients X, Y, for each component.  
 %   This is useful for computing quantities on the disk with the function F.
 % 

@diskfunv/vals2coeffs.m

@@ -1,21 +1,18 @@
-function [X, Y] = vals2coeffs(U,V)
+function [ X, Y ] = vals2coeffs( U,V )
 % VALS2COEFFS  componentwise conversion of matrices of values to
 % matrices of  Chebyshev-Fourier coefficients.
 %
-% U, V = VALS2COEFFS(X, Y) converts matrices X, Y of values representing 
+% U, V = VALS2COEFFS( X, Y ) converts matrices X, Y of values representing 
 % samples of a function from a tensor Chebyshev-Fourier grid 
 % to matrices U, V of Chebyshev-Fourier coefficients for the corresponding 
 % interpolants.
 % 
 %
 % See also COEFFS2VALS
 
-% Copyright 2017 by The University of Oxford and The Chebfun Developers.
+% Copyright 2019 by The University of Oxford and The Chebfun Developers.
 % See http://www.chebfun.org/ for Chebfun information. 
 
-%%
-% Empty check:
-
 
 X = diskfun.vals2coeffs(U); 
 Y = diskfun.vals2coeffs(V); 

@spherefun/coeffs2.m

@@ -1,10 +1,10 @@
-function varargout = coeffs2(f, m, n)
+function varargout = coeffs2( f, m, n )
 %COEFFS2   Double Fourier coefficients of a SPHEREFUN. 
 % 
-%   X = COEFFS2(F) returns the 2D Fourier modes of the spherefun, viewed
+%   X = COEFFS2( F ) returns the 2D Fourier modes of the spherefun, viewed
 %   as a doubly periodic function. 
 % 
-%   [C, D, R] = COEFFS2(F) returns a low rank approximation to the 2D
+%   [C, D, R] = COEFFS2( F ) returns a low rank approximation to the 2D
 %   Fourier modes.
 % 
 %   X = COEFFS2(F, M, N) returns bivariate coefficients with N Fourier 
@@ -13,6 +13,11 @@
 % Copyright 2017 by The University of Oxford and The Chebfun Developers.
 % See http://www.chebfun.org/ for Chebfun information.
 
+% empty check
+if isempty(f)
+    varargout = {}; 
+    return
+end
 
 % Calculate the CDR decomposition: 
 [C, D, R] = cdr(f); 

@spherefun/coeffs2spherefun.m

@@ -1,4 +1,4 @@
-function F = coeffs2spherefun(X)
+function F = coeffs2spherefun( X )
 %COEFFS2SPHEREFUN      Make a SPHEREFUN object from a matrix of Fourier
 %   coefficients. 
 %

@spherefun/vals2coeffs.m

@@ -1,13 +1,14 @@
-function varargout = vals2coeffs( U, varargin)
+function varargout = vals2coeffs( U, varargin )
 %VALS2COEFFS    Convert matrix of values to Fourier-Fourier coefficients. 
 % 
-% V = VALS2COEFFS( C ) converts a matrix C of values representing 
+% V = VALS2COEFFS( U ) converts a matrix U of values representing 
 % samples of a function from a tensor double Fourier sphere grid 
-% and converts them to a matrix V of Fourier-Fourier coefficients 
-% for the corresponding interpolant.
+% to a matrix V of 2D Fourier coefficients for the corresponding 
+% interpolant.
 % 
 % [U, S, V] = VALS2COEFFS( U, S, V ) the same as above but keeps 
-% everything in low rank form.
+% everything in low rank form. Here, U*S*V.' is a sample of 
+% values on the double Fourier sphere grid.
 % 
 % See also COEFFS2VALS
 

@spherefunv/coeffs2.m

@@ -1,11 +1,11 @@
-function varargout = coeffs2( f, varargin) 
+function varargout = coeffs2( f, varargin ) 
 %COEFFS2   componentwise double Fourier coefficients of a SPHEREFUNV. 
 % 
 %   [X, Y, Z] = COEFFS2( F ) returns the 2D Fourier modes for each component 
 %   of the SPHEREFUNV F, where each component is a doubly-periodic
-%   function.
+%   function on the double Fourier sphere.
 %  
-%   [X, Y] = COEFFS2(F, M, N) returns bivariate coefficients with N Fourier 
+%   [X, Y] = COEFFS2( F, M, N ) returns bivariate coefficients with N Fourier 
 %   modes in the latitude direction and M Fourier modes in the
 %   longitude direction.
 %
@@ -14,6 +14,14 @@
 % Copyright 2019 by The University of Oxford and The Chebfun Developers.
 % See http://www.chebfun.org/ for Chebfun information.
 
+
+
+%empty check
+if isempty(f)
+    varargout = {}; 
+    return
+end
+
 F1 = f.components{1};
 F2 = f.components{2}; 
 F3 = f.components{3}; 

@spherefunv/coeffs2spherefunv.m

@@ -1,8 +1,8 @@
-function F = coeffs2spherefunv(X, Y, Z)
+function F = coeffs2spherefunv( X, Y, Z )
 %COEFFS2SPHEREFUNV   Convert componentwise matrices of 2D Fourier 
 %   coefficients to a spherefunv. 
 % 
-%   F = coeffs2spherefunv(X, Y, Z) returns a spherefunv object F that has 
+%   F = coeffs2spherefunv( X, Y, Z ) returns a spherefunv object F that has 
 %   matrices of 2D Fourier coefficients X, Y, and Z for each component.  
 % 
 % See also SPHEREFUN/COEFFS2SPHEREFUN 

@spherefunv/coeffs2vals.m

@@ -1,4 +1,4 @@
-function [X,Y,Z] = coeffs2vals(U,V,W)
+function [ X,Y,Z ] = coeffs2vals( U,V,W )
 % COEFFS2VALS  componentwise conversion of 2D Fourier coefficient matrices
 % to values.
 %

@spherefunv/vals2coeffs.m

@@ -1,10 +1,10 @@
-function [U, V, W] = vals2coeffs(X,Y,Z)
+function [ U, V, W ] = vals2coeffs( X,Y,Z )
 % VALS2COEFFS  componentwise conversion of matrices of values to
 % matrices of 2D Fourier coefficients.
 %
-% U, V, W = VALS2COEFFS(X,Y, Z) converts matrices X, Y and Z of values sampled
-% from doubly periodic functions on equally-spaced tensor grids of the 
-% latitude-longitude domain [-pi, pi) x [-pi, pi) to matrices U, V and W, 
+% U, V, W = VALS2COEFFS( X,Y, Z ) converts matrices X, Y and Z of values 
+% sampled from doubly periodic functions on equally-spaced tensor grids of 
+% the domain [-pi, pi) x [-pi, pi) to matrices U, V and W, 
 % containing 2D Fourier coefficients for the corresponding interpolants.
 % 
 %