Merge pull request #2425 from chebfun/fix-diskfun-helptext

fix help text typo

@chebfun/chebpade.m

@@ -29,7 +29,13 @@
 
 % TODO:  Handle quasimatrices/array-valued CHEBFUNs.
 
-% TODO:  References?
+%   Reference:
+%   [1] Keith O. Geddes, Block structure in the Chebyshev–Padé table, SIAM J.
+%   Numer. Anal. 18 (1981) 844-861.
+%
+%   [2] Hans J. Maehly, Rational approximation for transcendental functions, 
+%   Proceedings of the International Conference on Information Processing,
+%   UNESCO Butterword, London, 1960.
 
 % Parse the inputs.
 if ( nargin == 2 )     % CHEBPADE(F, M)

@diskfun/mean.m

@@ -1,6 +1,6 @@
 function s = mean(f, dim)
 %MEAN   Average or mean value of a DISKFUN. 
-%   MEAN(F) takes the mean in the angular direction (default), i.e., 
+%   MEAN(F) takes the mean in the radial direction (default), i.e., 
 %          MEAN(F) = sum(F).
 %
 %   MEAN(F, DIM) takes the mean along the direction DIM. If DIM = 1 it is the
@@ -19,15 +19,15 @@
 end 
 
 if ( nargin == 1)
-    % Default to the angular direction.
+    % Default to the radial direction.
     dim = 1;    
 end
 
 s = sum(f, dim);
 if ( dim == 1 )
-    return; % Mean in the angular direction (default)
+    return; % Mean in the radial direction (default)
 elseif ( dim == 2 )
-    s = s / (2*pi); % Mean in the radial direction
+    s = s / (2*pi); % Mean in the angular direction
 else
     error('CHEBFUN:DISKFUN:mean:dim', ...
         'dim must be 1 or 2.')

@diskfun/sum.m

@@ -1,7 +1,7 @@
 function f = sum( f, dim )
 %SUM   Definite Integration of a DISKFUN.
-%   G = sum(F,DIM) where DIM is 1 or 2 integrates only over theta 
-%   (angular direction) or r (radial direction) respectively,
+%   G = sum(F,DIM) where DIM is 1 or 2 integrates only over r
+%   (radial direction) or theta (angular direction) respectively,
 %   and returns as its output a chebfun in the remaining variable.
 %
 %   G = sum(F) is the same as sum(F,1)