Re #1776 fixed kf_sphere_proj.m constructor, to have Ei as first para…

…meter

herbert_core/utilities/scientific/neutron_constants.m

@@ -3,9 +3,10 @@
 %
 %   >> s=neutron_constants      % return structure
 %   >> neutron_constants        % list constants
+%   >> val = neutron_constants(constant_name) % returns particular
+%            constant.
 
 
-mlock;  % for stability
 persistent structure
 
 if isempty(structure)
@@ -24,10 +25,16 @@
 end
 
 if nargout>0
-    if narin == 0
+    if nargin == 0
         s=structure;
     else
-        s = structure.(constant_name);
+        if isfield(structure,constant_name)
+            s = structure.(constant_name);
+        else
+            error('HERBERT:utilities:invalid_argument', ...
+                'name: "%s" is not a correct neutron constant name', ...
+                constant_name)
+        end
     end
 else
     nam=fieldnames(structure);

horace_core/sqw/coord_transform/@CurveProjBase/CurveProjBase.m

@@ -91,7 +91,7 @@
                     obj = obj.check_combo_arg();
                 end
             else
-                opt =  [sphere_proj.fields_to_save_(:);aProjectionBase.init_params(:)];
+                opt =  obj.init_order_fields();
                 [obj,remains] = ...
                     set_positional_and_key_val_arguments(obj,...
                     opt,false,varargin{:});
@@ -197,6 +197,16 @@
                 S.v = S.ex;
             end
         end
+        function flds = init_order_fields(~)
+            % Addition to serailizable interface allowing to reorder
+            % saveableFields in order, convenient for constructing a
+            % projection. While saveableFields specify public interface
+            % which fully defines projection, the convenient order of these
+            % fields in construction or init may be different as people may
+            % prefer define most important fields first and fields with
+            % reasonable defaults -- after them
+            flds = [sphere_proj.fields_to_save_(:);aProjectionBase.init_params(:)];
+        end
     end
     methods
         % Old ez,ex interface:

horace_core/sqw/coord_transform/@kf_sphere_proj/kf_sphere_proj.m

@@ -24,6 +24,11 @@
     %        The axis to calculate theta angle from.
     % v  -- [1,3] vector of hkl direction of x-axis of the spherical
     %       coordinate system, the axis to calculate Phi angle from.
+    % NOTE:
+    %       the idea of this projection is that u and v should be set to
+    %       the values of u,v vectors, used to obtain sqw object i.e. u
+    %       should coicide with beam direction and v selected to define the
+    %       uv plane, where rotation occurs.
     %
     % type-- 3-letter character array, defining the spherical
     %        coordinate system units (see type property below)
@@ -89,7 +94,7 @@
             ei = obj.Ei_;
         end
         function obj = set.Ei(obj,val)
-            if ~isnumeric(val)||numel(val)
+            if ~isnumeric(val)||~isscalar(val)
                 error('HORACE:kf_sphere_proj:invalid_arguments', ...
                     'Incident beam must be poisitive. Got %d',val);
             end
@@ -164,6 +169,15 @@
     %=====================================================================
     % SERIALIZABLE INTERFACE
     %----------------------------------------------------------------------
+    methods(Access=protected)
+        function flds = init_order_fields(obj)
+            % overloadeded field construction order to put incident energy
+            % first
+            flds = init_order_fields@CurveProjBase(obj);
+            flds = ['Ei';flds(:)];
+        end
+    end
+
     methods
         function  flds = saveableFields(obj)
             flds = saveableFields@sphere_proj(obj);