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Hi, I have the piece of code as shown below, when the matrix A is displayed, each value in it has been divided by 1e^3. I cant seem to figure out why, does anyone have any ideas?

clear all

clc

[ortho, cmap] = imread('Oban.TIF');

ortho = uint16(ortho);

count1 = 0 ;

peaks = zeros([],3) ; % to store i,j,ortho(i,j) in respective columns

sz = size(ortho);

md= median(ortho);

pks = zeros(sz(1),sz(2));

for i =2:sz(1)-1

for j =2:sz(2)-1

if ortho(i-1,j) < ortho(i,j) & ...

ortho(i+1,j-1) < ortho(i,j) & ...

ortho(i,j-1) < ortho(i,j) & ...

ortho(i,j+1) < ortho(i,j)

pks(i,j) = 1;

% fprintf("i=%d j=%d z=%d \n",i,j,ortho(i,j));

count1 = count1+1 ;

peaks(count1,:) = [i j ortho(i,j)] ;

end

end

end

% peaks

rand = randsample(1:length(peaks), 5);

randm = peaks(rand,:);

count2 = 0 ;

A = zeros([],3) ;

for m = 1:5

i = randm(m,1);

j = randm(m,2);

% fprintf('i is %d and j is %d \n',i,j);

R = worldfileread('concord_ortho_w.tfw', 'planar', size(ortho));

figure (5)

mapshow(ortho, cmap, R);

% LINE

Txx = i + 207000 ;

Txy = j + 909000;

Rxx = 210276;

Rxy = 910552;

hold on

h = plot([Txx Rxx],[Txy Rxy], 'b'); %draw line

Dx = Txx - Rxx;

Dy = Txy - Rxy;

Dsq = Dx^2 + Dy^2;

Dp = sqrt(Dsq);

Dm = Dp*25;

Dkm = Dm/1000;

Distance = string(Dkm);

text(Rxx, Rxy, 'Tx','Color','red','FontSize',14)

text(Txx, Txy, Distance,'Color','red','FontSize',14)

x = [Txx Rxx];

y = [Txy Rxy];

N = 20;

xi = linspace(x(1), x(2), N+1); %segment the line into n segments

yi = interp1(x, y, xi, 'linear');

Q = N ;

DistReso = Dm/Q;

plot(xi(2:end-1), yi(2:end-1), 'bp')

Elevationm = zeros(1,Q+1); %before the loop

for P = 1:Q %state values

format long

imag=imread('Oban.tif');

PointPx = Txx + (P*(Rxx-Txx)/N);

PointPy = Txy +(P*(Rxy-Txy)/N);

SubPlotxPRound = round(PointPx);

SubPlotyPRound = round(PointPy);

format long

ElevPx = (PointPx- 207000);

ElevPy = PointPy - 909000;

ElevPxRound = round(ElevPx);

ElevPyRound = round(ElevPy);

Elevationcm = imag(ElevPxRound,ElevPyRound);

Elevationm(1,P+1) = Elevationcm/100;

end

struct_Input = struct;

struct_Input.Frequency = 38000000000; % Frequency to calculate loss at (Hz)

struct_Input.Elevation = Elevationm; % terrain elevation profile, (list of points) (m)

struct_Input.Resolution = DistReso; % terrain input resolution (distance between points) (m)

struct_Input.TX_Height = 50; % Transmit antenna height above ground (m)

struct_Input.RX_Height = 200; % Recieve antenna height above ground (m)

struct_Input.eps = 4; % Soil dielectric

struct_Input.sgm = 50; % Surface conductivity

struct_Input.surfref = 260; % Surface refractivity

struct_Input.Climate = 5; % Climate, 1-Equitorial, 2-Continental Subtropical, 3-Maritime Tropical, 4-Desert

struct_Input.Polarization = 1; % 1 is vertical, 0 is horizontal.

struct_Input.Confidence = 0.95; % confidence for statistical analysis (.01 to .99)

struct_Input.Reliability = 0.9; % Reliability to calculate statistics for (.01 to .99)

myLRobj = CL_Propagation_RF_LR();

% myLRobj.test();

% struct_Output = point_to_point(myLRobj,struct_Input)

TS = 25;

dbloss = 361.6;

RS = TS - dbloss;

NF = -150;

SNR2 = RS - NF;

PL = dbloss;

F = -(0.5 * SNR2) + (0.5 * (PL/Dkm));

fprintf('i is %d, j is %d, fitness is %d. \n',i,j,F)

count2 = count2+1 ;

A(count2,:) = [i j F] ;

end

disp(A);

Walter Roberson
on 15 Feb 2021

Give the command

format long g

and disp(A) again. I think you will see the values you expect.

The default set by MATLAB is format short. If you looked very carefully at the very beginning of the output of the display, it would have said

1e3 *

meaning that you were intended to mentally multiply all the displayed values by 1000 .

Walter Roberson
on 15 Feb 2021

It's a "feature"

format short is the default because it creates compact output, and a lot of the time people really don't need to know more than 5 digits of precision. 5 digits is good enough most of the time. Unfortunately, the assumption in the display routines is that all rows and columns have the same relative weight, so that if one value is 123456 and another value is 42, that the 42 barely rates a digit of output by comparison. However a lot of the time that doesn't hold, and different columns might have different scales or different starting points and using a common scale factor gives very wrong understandings of the data...

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