MATLAB: How to find PDF, CDF and the probability at a certain point from histogram

histogramMATLAB

Suppose that I have an array of random numbers, e.g.

X=randn(1,1000);
hist(X,100);

Using the histogram ,I want to find and plot the PDF and CDF of X, and for a constant value a, I also want to find the probabilities P(X=a) and P(X<=a).

Any help would be appreciated. Thank you.

Best Answer

Is this homework? Hint: just take the counts return argument from hist() and normalize the counts array by the total number of counts. Then get cdf by using cumsum() on the normalized counts.

Related Solutions

MATLAB: Histogram with added density function

Try this:

clc; 
close all; 
rng('default');
datapoints{1} = exprnd(1 , [5,1]);
datapoints{2} = exprnd(1 , [50,1]);
datapoints{3} = exprnd(1 , [500,1]);
datapoints{4} = exprnd(1 , [5000,1]);
for i=1:numel(datapoints)
    ax = subplot(2,2,i);
    histogram(datapoints{i});
    dist = fitdist(datapoints{i}, 'Exponential');
    x_points = linspace(0, ax.XLim(2), 100);
    Pdf = pdf(dist, x_points);
    Cdf = cdf(dist, x_points);
    yyaxis right
    hold on
    plot(x_points, Pdf, 'r', 'LineWidth', 2, 'DisplayName', 'PDF');
    plot(x_points, Cdf, 'b', 'LineWidth', 2, 'DisplayName', 'CDF');
    legend
end

Result:

MATLAB: What mean ,hist word in matlab

It a frequency histogram

X = randn(1000,1);
hist(X)

It "bins" the input data and returns the number of data values that value in each bin.

You can get the actual counts and bin center with the optional output arguments:

 [counts,centers] = hist(X);

Best Answer

Related Solutions

MATLAB: Histogram with added density function

MATLAB: What mean ,hist word in matlab

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