MATLAB: How to plot a line with discontinuity

discontinuitynanplot

I need to plot a discontinuous line, I saw some of the answers but they dont fit to my problem. I have the following data: >> x= [ 5 15 30 50 80 115]; >> d= [ 0.9901 1.0184 0.8291 2.2491 NaN 0.0738]; and I need the graph to appear as a continuous line for the first 4 elements, then a gap, then the last element. What i get when I do >> plot(x,y) is a line the breaks at the fourth element and that is it

Best Answer

The problem is (at least I assume this), that you cannot see the last element. This happens, because it is a scalar. Such "points" are not visible in a line plot, because they do not have an extend.

x = [ 5 15 30 50 80 115];
d = [ 0.9901 1.0184 0.8291 2.2491 NaN 0.0738];
plot(x, d)

But you can draw the points also, which might be the better choice at all for a discontinuous signal:

plot(x, d, '-o')

Unfortunately you did not mention, how you want to look the output like.

Related Solutions

MATLAB: Multiplying by inverse of a matrix

You are essentially "dividing" by the X'*X quantity, so that is what needs to appear on the "bottom" of the slash. E.g.,

>> alpha = 0.5;
>> X = [0.6 0.9; 0.9 0.5];
>> alpha*inv(X'*X)
ans =
    2.0377   -1.9031
   -1.9031    2.2491
>> (X'*X)\eye(2)*alpha
ans =
    2.0377   -1.9031
   -1.9031    2.2491
>> alpha*eye(2)/(X'*X)
ans =
    2.0377   -1.9031
   -1.9031    2.2491

Or you can think of it this way. Start with this definition:

inv(X'*X) * (X'*X) = eye(2)

and solve for the inverse:

inv(X'*X) = eye(2)/(X'*X)

Similarly, starting with this definition:

(X'*X) * inv(X'*X) = eye(2)

yields

inv(X'*X) = (X'*X)\eye(2)

Then just multiply by alpha.

MATLAB: Plot smooth curve through discreet points

First you have to interpolate x depending on y. Next, you have to do the interpolation separately for each of the discontinuous segments. Since the function has discontinuities after every 5 data points, we don't have to figure out the discontinuities but interpolated every set of 5 points separately (the xi_end, yi_end denote the last data point of the previous segment to plot the horizontal lines):

ind0 = 1:5; xi_end = NaN; yi_end= NaN;  
for i = 1:numel(y)/numel(ind0)
  ind = ind0 + 5*(i-1);
  yi = linspace(y(ind(1)), y(ind(end)));
  xi = interp1(y(ind), x(ind), yi, 'spline');
  plot([xi_end xi], [yi_end yi])
  hold on
  xi_end = xi(end);
  yi_end = yi(end);
end

Best Answer

Related Solutions

MATLAB: Multiplying by inverse of a matrix

MATLAB: Plot smooth curve through discreet points

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