MATLAB: Chap vector to matrix with special structure.

MATLABmatrix manipulation

I have a collumn vector consisting of n elemtents (size nx1):

P=[P1 ….. Pn]'

What I which to do, is transform this into a matrix with a certain number of rows. This is best explained by an example e.g. k=3 rows:

M=
P1 P2 ... Pn-2
P2 P3 ... Pn-1
P3 P4 ... Pn
Or k=4 rows
M=
P1 P2 ... Pn-3
P2 P3 ... Pn-2
P3 P4 ... Pn-1
P4 P5 ... Pn
In general
M=
P1 P2 ...  Pn-k+1
P2 P3
.  .
.  .
Pk Pk+1 ... Pn

I hope my point is clear and you can help me. I'm performing this operation such that I can perform a multiplication more efficiently.

Thank you guys in advance!

Best Answer

My own answer:

dum=hankel(C)
M=dum(1:k,1:n-k+1)

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MATLAB: How to access a structure array using a loop

First, note that with your example, at the end p is a structure with just one field 'p10'. To create the structure you want:

p = struct('p1', {p1}, 'p2', {p2}, 'p3', {p3}, ...)

Also note that you don't need to put the field contents into a cell array, unless this content is itself a cell array. so:

 p = struct('p1', p1, 'p2', p2, ...)

may work just as well.

Secondly, your for loop is not going to work, ['p1' 'p2' 'p3' ...] is exactly the same as 'p1p2p3....', and i will take in turn the values 'p', then '1', then 'p' again, then '2', etc. You need to use a cell array

Finally, to use dynamic field names, you enclose the variable holding the field name in round brackets ().

So:

p = struct('p1',{p1}, 'p2',{p2}, 'p3',{p3}, 'p4',{p4}), 'p5',{p5}, 'p6',{p6}, 'p7',{p7}, 
'p8',{p8}, 'p9',{p9}, 'p10',{p10});
for fn = {'p1', 'p2', 'p3', 'p4', 'p5', 'p6', 'p7', 'p8', 'p9', 'p10'}
%or better: for fn = fieldnames(p)'
   o = p.(fn{1});
end

MATLAB: How do i merge the first and second cylinder surface

Hello NurFadhilah,

I believe this could be solved by substracting the difference in height between the second and third surfaces from Z2 and Z3. Please see attached screenshot. This could be implemented in the code as shown in variables Z2 and Z3 below.

Z2 = [z9 z12]-0.09031;

Z3 =[z12 z9]-0.09031;

Hope this helps!

Best Answer

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MATLAB: How to access a structure array using a loop

MATLAB: How do i merge the first and second cylinder surface

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