TNK055 Matlab part

Basic syntax

Reference particular element in a vector v at index n	v(n)	Documentation
Assign new value to an element in a vector v at index n	v(n) = new_value	Documentation
Reference particular element in a matrix M at row row and column column	M(row, column)	Documentation
Assign new value to an element in a matrix M at row row and column column	M(row, column) = new_value	Documentation
Refer to all elements in a row n in a matrix M	M(n, :)	Documentation
Refer to all elements in a column n in a matrix M	M(:, n)	Documentation
Number of rows in a matrix M	size(M, 1)	Documentation
Number of columns in a matrix M	size(M, 2)	Documentation
Number of elements in a vector v	length(v)	Documentation
Print value of a variable var	disp(var)	Documentation
Clear workspace	clear;	Documentation
Create regularly-spaced vector starting from the number from to the number to with step step	v = from:step:to	Documentation
Create unit-spaced vector starting from the number from to the number to (the same as from:1:to)	v = from:to	Documentation
Square root of x	sqrt(x) or (x)^0.5 or (x)^(1/2)	Documentation
And	&&	Documentation
Or	||	Documentation
Not	~	Documentation
Determine equality	a == b	Documentation
Determine inequality	a ~= b	Documentation
Order of operations in Matlab	See documentation	Documentation

if, elseif, else

Execute statements if condition is true. Documentation

if condition
  statements
elseif another_condition
  statements
else
  statements
end

for loop

Repeat statement for each element in a vector. At each iteration it puts next element from the vector values to the variable value. Documentation

for value = values
 statements
end

while loop

Repeat statement when condition is true. Documentation

while condition
  statements
end

function

Declare a function with name name, where y1,...,yN are output variables (put your variables instead of ...) and x1,...,xM are input variables. Documentation

function [y1,...,yN] = name(x1,...,xM)

Useful functions

find

Find indices and values of nonzero elements Documentation

a = [-1, 6, 0, 4, 6];
indices1 = find(a > 1); % indices1 == [2, 4, 5]
indices2 = find(a == 6); % indices2 == [2, 5]

To select values from the vector use

a = [-1, 6, 0, 4, 6];
indices = find(a > 1); % indices1 == [2, 4, 5]
values = a(indices); % values == [6, 4, 6]

To find string in a cell array of strings use contains():

A = {'fish', 'dog', 'cat', 'horse'};
index = find(contains(A, 'dog')); % index == 2

Or ismember() (returns an array with 1 where the data in A is found in B):

A = {'dog','cat','fish','horse'};
B = {'dog','mouse','fish'};
res = ismember(A, B); % res == [true, false, true, false] or [1, 0, 1, 0]

azimuth

Azimuth between points Documentation

segment_start_point = [59.6569444500000	17.9522222166667]; % lat and lon
segment_end_point = [59.6519444500000	17.9186111166667]; % lat and lon

result = azimuth(segment_start_point(1), segment_start_point(2), segment_end_point(1), segment_end_point(2)); % result == 253.6074

unique

Unique values in array Documentation

a = [3, 6, 4, 3, 4, 5];
result = unique(a); % result == [3, 4, 5, 6]

Unique also works with matrices:

a = [3, 6;
4, 3;
3, 6];
result = unique(a, 'rows'); % result == [3, 6; 4, 3]

histogram

Histogram plot Documentation

a = [3, 6, 4, 3, 4, 5];
histogram(a); % try it!

Number of bins can be passed in the second argument of the function:

a = [3, 6, 4, 3, 4, 5];
histogram(a, 2); % try it!

Also, bins can be defined manually:

a = [3, 6, 4, 3, 4, 5];
histogram(a, [0, 3, 5, 6]); % try it!

Bins can be named:

a = [4, 3, 5];
histogram('Categories', {'First', 'Second', 'Third'}, 'BinCounts', a); % try it!

intersect

Set intersection of two arrays Documentation

A = [7 1 7 7 4];
B = [7 0 4 4 0];
C = intersect(A,B); % C == [4, 7]

Also intersect works with matrices

A = [2 2 2; 0 0 1; 1 2 3; 1 1 1];
B = [1 2 3; 2 2 2; 2 2 0];
C = intersect(A, B, 'rows'); % C == [1, 2, 3; 2, 2, 2]

strsplit

Split string at specified delimeter Documentation

res = strsplit('ABCD_DCBA', '_'); % res == {'ABCD', 'DCBA'}

distance

Distance between points on sphere or ellipsoid Documentation

arc_length = distance(37, -76 , 37, -9);

deg2nm

Convert spherical distance from degrees to nautical miles Documentation

arc_length_in_nm = deg2nm(distance(37, -76 , 37, -9));