A way to compute dot product of an array and a vector

14 vues (au cours des 30 derniers jours)
Elina Park
Elina Park le 26 Sep 2018
Modifié(e) : Torsten le 8 Juil 2023
Hi, So if I have a 2-D array such as
[1 2
3 4
5 6]
and a vector such as
[7 8]
I want to have matlab calculate the dot product of the rows of the array and the vector, and save the results as a column vector. How can I do this?

Réponse acceptée

Walter Roberson
Walter Roberson le 26 Sep 2018
[1 2
3 4
5 6] * [7 8].'
  2 commentaires
Francesco Bernardini
Francesco Bernardini le 8 Juil 2023
Hi, thank you for the answer, it solved my problem;
however, is the dot before the ' needed?
Usually it means elementwise-operation but here I don't see the connection with the transposition;
Torsten
Torsten le 8 Juil 2023
Modifié(e) : Torsten le 8 Juil 2023
.' means: usual transpose
' means: conjugate transpose
If the arrays are all real-valued, both operations give the same result. If they are complex-valued - not.
a = [1 2];
a'
ans = 2×1
1 2
a.'
ans = 2×1
1 2
a = [1 + 1i , 2-3*1i];
a'
ans =
1.0000 - 1.0000i 2.0000 + 3.0000i
a.'
ans =
1.0000 + 1.0000i 2.0000 - 3.0000i

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