MATLAB Answers

how can i make this loop?

16 views (last 30 days)
Mamad Mamadi
Mamad Mamadi on 19 Jan 2020
Commented: Star Strider on 21 Jan 2020
hi friends im new in matlab could you please help me in this problem.
I have an equations A ; A=x*a-b
x=[1 2 5 8 10];
i want to put x values into equation A one by one to solve it, which i mean x1=1, to solve A1 and x2=2 to solve A2 and so on.
after that i want to use the results that i found in this equation B= (A1...An / c).
thanks

  0 Comments

Sign in to comment.

Answers (1)

Star Strider
Star Strider on 19 Jan 2020
No loop needed.
If you want to calculate ‘A’ with ‘a’ and ‘b’ already defined numerically as scalars, or if ‘b’ is a vector the same size as ‘x’, just do this:
A = x*a-b
If ‘a’ is a vector with the same dimensions as ‘x’, use element-wise multiplication:
A = x.*a+b
You might need to use bsxfun to do the vector multiplications if you have R2016a or earlier.

  6 Comments

Show 3 older comments
Star Strider
Star Strider on 19 Jan 2020
Then ‘A’ is a (20x5) matrix:
a = rand(20,1);
x=[1 2 5 8 10];
b = rand;
A = a*x - b;
If you have a MATLAB version (release) earlier than R2016b, calculate ‘A’ as:
A = bsxfun(@times, x, a) -b;
to get the same result.
Mamad Mamadi
Mamad Mamadi on 21 Jan 2020
sad to say i use the old version R2013a :(
Star Strider
Star Strider on 21 Jan 2020
The bsxfun function was introduced in R2007a, so you can use it to do the multiplications. I believe the additions always used explicit expansion. If they do not, use bsxfun for those as well:
A = bsxfun(@minus, bsxfun(@times, x, a), b)
That should work.
The loops are all still there, however they are hidden in the bsxfun calls.

Sign in to comment.

Sign in to answer this question.