% weight.m ----------------------------------------------------------
% - The SubPlot argument is used to create an upper and lower axis.
% The lower axis contains 4 traces showing the magnitude of 4
% different weighting functions used in sound level meters (as
% defined by IEC 651). The upper axis also contains 4 traces showing
% the same 4 functions except in dB instead of the linear units used
% for the lower axis. The middle axis shows the inverse of the linear
% magnitude traces, which isn't particularly interesting except that
% I wanted to demonstrate the use of three axes.
% - Normally plt only puts one trace on each subplot except for the
% main (lower) axis. So in this case (with 12 traces) plt puts 10
% traces on the lower axis and one on the other two. Since we really
% want 4 and 4 and 4, the 'SubTrace' parameter is used to specify
% exactly which traces should be on each axis. However the plt cursoring
% functions have not been designed to handle the 'SubTrace' parameter
% so weight.m will have to contain some of its own cursor code.
% - Note that when you cursor any trace in the lower axis, you get
% the y-axis readout for all three axes, and the cursor in the upper
% two axes automatically moves to the same trace and the same x position.
% The subplot argument usually will cause plt to do this synchronization,
% however since that only deals with a single trace for the sublots we
% have to use the 'moveCB' cursor callback (and case 1 of the switch
% command) to do this synchronization.
% - The traceID callback ('TIDcback') insures that the traceID box
% controls the upper axis traces as well (case 2 of the switch)
% - Note the LineWidth argument in the plt call. This illustrates how
% any line property may be included in the calling sequence.
% ----- Author: ----- Paul Mennen
% ----- Email: ----- paul@mennen.org
function weight()
f = 1000*10.^(-2 : 2/63 : 1.33); % x axis for plot
g = f.^2;
Wc = g ./ ((g + 20.6^2) .* (g + 12200^2)); % C weight
Wb = Wc .* sqrt(g ./ (g + 158.5^2)); % B weight
Wa = Wc .* g ./ sqrt((g + 107.7^2) .* (g + 737.9^2)); % A weight
Wd = f .* sqrt( ((1037918.48-g).^2 + 1080768.16*g) ./ ...
(((9837328-g).^2 + 11723776*g) .* (g+79919.29) .* (g+1345600)));
[m ref] = min(abs(f-1000)); % use 1000 Hz as the reference frequency
W = [Wa/Wa(ref); Wb/Wb(ref); Wc/Wc(ref); Wd/Wd(ref)]; % normalize to reference
ctrace = [0 .9 0; 1 0 1; 0 1 1; 1 1 0]; % color for A/B/C/D weighting respectively
S.lh = plt(f,[W; 1./W; 20*log10(W)],'FigName','A B C & D Weighting','EnaPre',[0 0],...
'LineWidth',{2 2 2 2 1 1 1 1 1 1 1 1},'TIDcback',@tidCB,'SubPlot',[40 20 40],...
'ENAcur',[1 1 1 1 0 0 0],'Xlim',f([1 end]),'Ylim',[-.05 1.25],...
'SubTrace',[4 4 4],'TRACEid',{'A weight' 'B weight' 'C weight' 'D weight'},...
'Options','Xlog-X-Y','LabelX','Hz','LabelY',{'Magnitude' '1/Mag' 'dB'},...
'FigBKc',[0 0 .15],'PltBKc',[.07 0 0],...
'Ctrace',ctrace,'Position',[30 50 900 650]);
S.ax = getappdata(gcf,'axis');
S.cid = getappdata(gcf,'cid');
plt('cursor',S.cid(2),'set','ylim',[0 4]); % set y limits
plt('cursor',S.cid(3),'set','ylim',[-55 15]);
bf = get(S.lh(1:4),{'buttond'});
set(S.lh(5:8), {'buttond'},bf); % Three axes, each having 4 lines
set(S.lh(9:12),{'buttond'},bf);
plt('cursor',S.cid(1),'set','moveCB',{@curCB,S});
curCB(S);
set(gcf,'user',S); % save for traceID callback
function curCB(S) % cursor callback (moveCB)
[n h] = plt('cursor',S.cid(1),'get','activeLine');
[xy k] = plt('cursor',S.cid(1),'get','position');
x = real(xy);
n = min(4,n);
y2 = get(S.lh(n+4),'y'); y2 = y2(k);
y3 = get(S.lh(n+8),'y'); y3 = y3(k);
c = get(h,'color');
e = findobj(gcf,'style','edit');
set(e([6 2]),'Backgr',c, ...
{'str'},{['1/' plt('ftoa','%5w',y2)]; sprintf('%4.2fdB',y3);})
set(findobj(S.ax(2),'markersize',8),'x',x,'y',y2,'color',c);
set(findobj(S.ax(3),'markersize',8),'x',x,'y',y3,'color',c);
%end function curCB
function tidCB() % traceID callback
S = get(gcf,'user');
a = get(S.lh(1:4),{'vis'});
set(S.lh(5:12),{'vis'},[a; a])
% end function tidCB
