Introduction to MATLAB - Numerical Methods in Engineering with MATLAB - page 3

if A(i,k) ˜= 0
lambda = A(i,k)/A(k,k);
A(i,k+1:n) = A(i,k+1:n) - lambda*A(k,k+1:n);
b(i)= b(i) - lambda*b(k);

end

end

end
%--------------Back substitution phase-----------
fork=n:-1:1
b(k) = (b(k) - A(k,k+1:n)*b(k+1:n))/A(k,k);

end

Simultaneousequationscan also be solvedinMATLABwith the simple command

b (see below).
MATLAB can beoperatedinthe interactive modethrough its command window,
whereeach command isexecuted immediatelyuponits entry. In this modeMATLAB
acts like an electroniccalculator. Here is an example of an interactive session for the
solution of simultaneousequations:

\

A

>>A=[210;-122;014];%Input3x3matrix
>>b=[1;2;3]; %Inputcolumnvector

>>soln=A\b %SolveA*x=bbyleftdivision

soln =
0.2500
0.5000
0.6250

isMATLAB's promptfor input. The percentsign ( %) marks the
beginning of a comment.Asemicolon (;)hastwofunctions:itsuppresses printout
of intermediate results and separates the rowsofamatrix. Without a terminating
semicolon, the result of a command wouldbe displayed. For example, omission of
the last semicoloninthe line defining the matrix A wouldresult in

The symbol >>

>>A=[210;-122;014]
A=

2 1 0

-1 2 2

0 1 4