MATLAB: Given y, how to find the value for x

interp1 for x value

I plotted the function:

x = 0:0.01:2;

y=(1.96./x).*(1-exp(-0.83.*x));

I want to know the x value when y=1. I want to use an interp1 function, but that will only give me y values. Is there a function to find x values?

Also, I can't get my x-axis correct. I want it to span 0-2 (the value I'm looking for is around 1.3) with step sizes of 0.001 (for more precision). Currently, it goes 0 to 200 and I'm at a loss of what to do.

Thanks for the help.

Best Answer

>> f2 = @(y)arrayfun(@(y)fzero(@(x)1.96./x.*(1-exp(-0.83.*x))-y,1),y);
>> f2([.03 1 12])
ans = 
       65.333    1.2859   -3.8605

Related Solutions

MATLAB: How to find X Value given Y value and show the point on a plot

x = 0:1:25;
y = exp(-0.03*x);
figure;
semilogy(x,y);
%
yi = 0.5 ;
xi = interp1(y,x,yi) ;
hold on
semilogy(xi,yi,'*r')

MATLAB: ButtonGroup

The lines I changed are marked with a %%

   function [] = test(varargin)
   N.fh=figure('units','pixels',...
      'position',[500 250 300 400],...
      'color',[0.73 0.83 0.96],...
      'menubar','none',...
      'name','Title',...
      'numbertitle','off',...
      'resize','off');
   N.bg = uibuttongroup('unit','pix',...
      'position',[15 25 270 55],...
      'title','Back Ground Color',...
      'fontsize',9,...
      'backgroundcolor',[0.73 0.83 0.96],...
      'foregroundcolor',[0.08 0.17 0.55]);
   N.blue = uicontrol(N.bg,...
      'style','rad',...
      'unit','pix',...
      'position',[15 15 50 15],...
      'string','Blue',...
      'value',1,...
      'backgroundcolor',[0.73 0.83 0.96]);
   N.green = uicontrol(N.bg,...
      'style','rad',...
      'unit','pix',...
      'position',[110 15 50 15],...
      'string','Green',...
      'value',0,...
      'backgroundcolor',[0.73 0.83 0.96]);
   N.gray = uicontrol(N.bg,...
      'style','rad',...
      'unit','pix',...
      'position',[200 15 50 15],...
      'string','Gray',...
      'value',0,...
      'backgroundcolor',[0.73 0.83 0.96]);
   set([N.blue,N.green,N.gray],'callback',{@bg_call,N})  %%1
   function [] = bg_call(varargin)
   N = varargin{3};
   switch findobj(get(N.bg,'SelectedObject'))            %%2
      case N.blue
     set(N.fh,'color',[0.73 0.83 0.96]);                 %%3


      case N.green
     set(N.fh,'color',[0.6 1 0.6]);                      %%3
      case N.gray
     set(N.fh,'color',[0.8 0.8 0.8]);                    %%3
   end

For %%1, you forgot the word 'callback' and you were trying to assign the callback to the buttongroup itself, not the buttons. The alternative would be to use the selectionchangefcn of the buttongroup.
For %%2, you used the field data2, but never assigned a field data2. Also, you do not need to use FINDOBJ here, you could replace this with varargin{1}.
For %%3, you referenced N.figure, but there was no field with this name in N. You meant N.fh.

Best Answer

Related Solutions

MATLAB: How to find X Value given Y value and show the point on a plot

MATLAB: ButtonGroup

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