Happy Pi Day

Posted by Cleve Moler, March 14, 2018

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Pi Day

Happy Pi Day, 3/14.

Here are 10,000 digits of π. Notice the six consecutive 9's in the sixth row, digits 763 through 768.

    n = 100;

    % Get pi from Symbolic Toolbox.

    p = vpa(pi,n^2);

    % Convert digits to characters, then to individual integers.

    p = char(p);
    p(2) = [];  % Decimal point
    p = p - '0';
    p(end+1:n^2) = 0;

    % Square array

    P = reshape(p,n,n)';

    % Extra row and column to satisfy pcolor.

    P(n+1,n+1) = NaN;

    % Plot with pcolor.

    pcolor(P)
    axis square
    axis off

    % Title
    title('\pi','fontsize',24)

    % Make room for colorbar

    pos = get(gca,'pos') - [.05 0 .0 0];
    set(gca,'ydir','rev','pos',pos)

    % Custom colorbar.

    a = axes('pos',[.80 .60 .02 .30]);
    y = (0:9)';
    y(11,2) = NaN;
    pcolor(y)
    set(a,'xtick',[],'ydir','rev','ytick',(1.5:1:10.5)', ...
       'yaxislocation','right', ...
       'yticklabel',{' 0',' 1',' 2',' 3',' 4',' 5',' 6',' 7',' 8',' 9'})