Ascending order-room modes

Hi all,

I created a script in order to calculate room modes using this formula : f = ( c/2 ) * ( sqrt( ((n/L))^2 + ((n/w))^2 + ((n/h))^2 ) )

L, w, h are the length,width and height and n:0,1,2,3,4 , c=speed of sound

So, I calculated in such a way that the different mode combinations are illustrated separately. Now, I want to put ALL the results that I found into one vector/matrix in ascending order. I tried to do something with the "sort" command but it couldn't work with all these matrices. Can someone help on this?

That's the code:

% Room Mode Calculator RC1

% f = ( c/2 ) * ( sqrt( ((nL/L))^2 + ((nw/w))^2 + ((nh/h))^2 ) )

clear

tic

c = 344 ; % speed of sound (m/s)

fL=zeros(1,9); % initialize vector
fw=zeros(1,9); % initialize vector
fh=zeros(1,9); % initialize vector

w= 2.20 ;
L= 3.50 ;
h= 3.02 ;

% AXIAL MODES

for n = 1: 9

fL(n) = (c/2) * (n/L) ;
fw(n) = (c/2) * (n/w) ;
fh(n) = (c/2) * (n/h) ;

end

% Tangential modes

fLw = zeros(1,4);
fwh = zeros(1,4);
fLh = zeros(1,4);

for nL= 1:4
for nw = 1:4

fLw(nL,nw) = ( c/2 ) * ( sqrt( ((nL/L))^2 + ((nw/w))^2 )) ;

for nh = 1:4

fwh(nw,nh) = ( c/2 ) * ( sqrt( ((nw/w))^2 + ((nh/h))^2 )) ;

fLh(nL,nh) = ( c/2 ) * ( sqrt( ((nL/L))^2 + ((nh/h))^2 )) ;

end

end

end

% Oblique Modes

fLwh = zeros(1,2);

for nL= 1:2

for nw = 1:2

for nh = 1:2

fLwh(nL,nw,nh) = ( c/2 ) * ( sqrt( ((nL/L))^2 + ((nw/w))^2 + ((nh/h))^2 ) ) ;

end
end

end

' AXIAL MODES '

fL
fw
fh

'TANGENTIAL MODES'

fLw
fLh
fwh

'OBLIQUE MODES'

fLwh

toc

So, how can I put all the results into one vector or matrix and place them in ascending order? I always have problems with matlab and most of the times with easy things. I can not understand well its way of "thinking"..

Thanks in advance,

Aris

Answer 1

[Oleg Komarov]

Your code can be vectorized to:

c  = 344; % speed of sound (m/s)
w  = 2.20;
L  = 3.50;
h  = 3.02;

% AXIAL MODES
n = 1:9;
fL = c/2 .* n/L;
fw = c/2 .* n/w;
fh = c/2 .* n/h;

% Tangential modes
nL = 1:4;
nw = 1:4;
nh = 1:4;

fLw = c/2 * sqrt(bsxfun(@plus, (nL.'/L).^2, (nw/w).^2));
fwh = c/2 * sqrt(bsxfun(@plus, (nw.'/w).^2, (nh/h).^2));
fLh = c/2 * sqrt(bsxfun(@plus, (nL.'/L).^2, (nh/h).^2));

% Oblique Modes
fLwh = c/2 * sqrt(bsxfun(@plus,(fLw(1:2,1:2) * 2/c).^2, permute(nh(1:2)/h,[3 1 2]).^2));

• In your previous code you didn't preallocate correctly for the tangential modes and oblique ones.
• Also the fLh depends on nL and nh but its calculation is nested into the loop for nw as well, which means that you calculate it several times redundantly overwrtiting the same results.

Now the MAIN question:

- Do you want fL,fw,fh,fLw,fwh,fLh and fLwh all together sorted?

EDIT

[srt, idx] = sort([fL(:);fw(:);fh(:);fLw(:);fwh(:);fLh(:);fLwh(:)])

[Nikolas Nikola]

Thanks for your response. Answering to your last question. Yes, at the end I want all the variables sorted together.

I haven't check yet the code you have sent. When I do i will answer properly. However, I think that my results are correct with my way, as well. It is not an efficient way though. I will check it again.

I made this quick response in order to answer to your last question.

Thanks again!

[Nikolas Nikola]

Thank you very much. That is what I need.