Distance within radius from a point (Lat,lon)

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format short g;
format compact;
fontSize = 15;
fprintf('Beginning to run %s.m ...\n', mfilename);
% Read in multiple points.
filename1 = fullfile(pwd, 'ascii.xlsx');
[d1,tex] = xlsread(filename1);
lat = d1(:,2)
lon = d1(:,1)
% Read in single point.
filename2 = fullfile(pwd, 'MYPOINT.xlsx');
[d2,tex] = xlsread(filename2);
lat1 = d2(:,2)
lon1 = d2(:,1)
% Plot a circle around MYPOINT
radius = 20; 
centerX = lat1;
centerY = lon1;
lightGreen = [.9, 1, .9];
rectangle('Position',[centerX - radius, centerY - radius, radius*2, radius*2],...
    'Curvature',[1,1],...
    'FaceColor',lightGreen);
axis equal;
% Plot the multiple points.
hold on;
plot(lat, lon, 'b.', 'MarkerSize', 20);
grid on;
xlabel('x = latitude', 'FontSize', fontSize);
ylabel('y = longitude', 'FontSize', fontSize);
caption = sprintf('%d points in blue, 1 point in red', size(lat, 1));
title(caption, 'FontSize', fontSize);
% Plot the single MYPOINT.
xline(lat1, 'Color', 'r', 'LineWidth', 2);
yline(lon1, 'Color', 'r', 'LineWidth', 2);
plot(lat1, lon1, 'r.', 'LineWidth', 2, 'MarkerSize', 50);
% Compute distances.
distances = sqrt((lat - lat1).^2 + (lon - lon1) .^ 2);
% Find row indexes where the distance is less than 20 km.
within20km = distances <= 20;
% Extract only those close points from the set of all points.
closePoints = [lat(within20km), lon(within20km)]
% Plot them.
plot(lat(:, 1), closePoints(:, 2), 'ro', 'MarkerSize', 20);
grid on;
fprintf('Done running %s.m.\n', mfilename);