hi, i have 2 different matrix with same dimensions and i need to know the min value against 2 values in the same position:
A=[ 0 1 3 5 6]
[2 3 5 8 9]
B=[2 2 4 7 8]
[3 5 7 9 10]
the algorithm confront the zero in first row first column of A with the 2 in first row first column of B and show the min value (0), so for the second row first column of each matrix and so on...i used a for cycle, but i want to know if i can try without any cycle.
In my cicle i use this:
for i 1:size(A)
find(A(1,:)<B(1,:)
end
how can i confront only element by element in the same position without any cycle?
i also have to use the elements of a matrix to do a scalar product using each element in a position and inserting it into a vector:
for i=1:length(A)
for j=1:N (size of rows)
ps1(i,j)=[A(i,j) 0]*[1 0]';
end
end
there is any way to do this without cycles?
i need the value in every position and that value is putted into a vector, then i make the scalar product with [1 0].
Tnx to all for the reply!

1 comentario

Stephen23
Stephen23 el 13 de Sept. de 2019
See Matt J's answer for the simplest and most efficient solution.

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 Respuesta aceptada

KALYAN ACHARJYA
KALYAN ACHARJYA el 13 de Sept. de 2019
Editada: KALYAN ACHARJYA el 13 de Sept. de 2019

0 votos

"i have 2 different matrix with same dimensions and i need to know the min value against 2 values in the same position:"
A=randi(10,[2,5]) % Random 2x5 A Matrix
B=randi(10,[2,5]) % Random 2x5 B Matrix
result=(A<=B).*A+(A>B).*B

8 comentarios

Dario Riviezzo
Dario Riviezzo el 13 de Sept. de 2019
wow it works!!! tnx a lot!
KALYAN ACHARJYA
KALYAN ACHARJYA el 13 de Sept. de 2019
My pleasure
Dario Riviezzo
Dario Riviezzo el 13 de Sept. de 2019
if i have a matrix and a vector, can i sum the single elements of the vector on each row of a matrix without a cycle?
A=[ 0 1 3 5 6]
[2 3 5 8 9]
B[1 1 1 1 1]
C=[1 2 4 6 7]
[3 4 6 9 10]
KALYAN ACHARJYA
KALYAN ACHARJYA el 13 de Sept. de 2019
Editada: KALYAN ACHARJYA el 13 de Sept. de 2019
If the both matrices having same size (A and B)
A=[0 1 3 5 6;2 3 5 8 9]
[r c]=size(A)
B=ones(r,c)
C=A+B
If not (same size), one option to zero pad, then add.
madhan ravi
madhan ravi el 13 de Sept. de 2019
Kalyan is missing the uniqueness of MATLAB , it’s simply:
A+B % bsxfun() prior to 2016b
KALYAN ACHARJYA
KALYAN ACHARJYA el 13 de Sept. de 2019
Yes @Madhan
Dario Riviezzo
Dario Riviezzo el 13 de Sept. de 2019
the second matrix (B) isn't made only of 1...i wrote that for an example, but it could be anything (with the same size row of A)
Dario Riviezzo
Dario Riviezzo el 13 de Sept. de 2019
mmh thinking on this problem i can simply copy the same row to make a matrix with same dimension of the first, then simply add :)
u are teaching to me how to think on matrix!

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Más respuestas (2)

Matt J
Matt J el 13 de Sept. de 2019

2 votos

min(A(1,:), B(1,:))
Dario Riviezzo
Dario Riviezzo el 13 de Sept. de 2019

0 votos

still need this:
i also have to use the elements of a matrix to do a scalar product using each element in a position and inserting it into a vector:
for i=1:length(A)
for j=1:N (size of rows)
ps1(i,j)=[A(i,j) 0]*[1 0]';
end
end
there is any way to do this without cycles?
i need the value in every position and that value is putted into a vector, then i make the scalar product with [1 0].
Tnx to all for the reply!

1 comentario

Matt J
Matt J el 13 de Sept. de 2019
Editada: Matt J el 13 de Sept. de 2019
But ps1(i,j)=[A(i,j) 0]*[1 0]'; is the same as ps1(i,j)=A(i,j). Example,
>> [3,0]*[1,0]'
ans =
3
The whole loop is therefore equivalent to the trivial single command,
ps1=A;

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