Subtracting in matrix, column to column (Basic MatLab)?
显示 更早的评论
Given a 45×48 matrix, type a single command that subtracts column 36 from column 44
i answered this but it pops up as Error: Invalid use of operator. Is there something wrong or should it be in different type of form.
(:,36)-(:,44)
采纳的回答
Star Strider
2019-8-11
Your idea is essentially correct. I have no idea what the question wants.
Perhaps providing a matrix and a reference to it will work:
A = rand(45,48);
col_dif = A(:,36)-A(:,44)
6 个评论
John wick
2019-8-11
Star Strider
2019-8-11
‘... subtracts column 36 from column 44 ...’
I missed the obvious!
Try this instead:
col_dif = A(:,44)-A(:,36)
John wick
2019-8-11
Star Strider
2019-8-11
Because the instruction is that the operation ‘... subtracts column 36 from column 44 ...’, and
col_dif = A(:,44)-A(:,36)
is the correct operation to subtract column 36 from column 44.
The reference to column 44 must come first in the order of operations, then the subtraction operation and then the value to be subtracted from column 44, here column 36. (There are other ways to code that subtraction and still get the correct result, however this is the most efficient.)
John wick
2019-8-11
Star Strider
2019-8-11
As always, my pleasure!
更多回答（1 个）
Image Analyst
2019-8-11
编辑：Image Analyst
2019-8-11
You need to put the matrix name in there, and a result variables, like
result = m(:,44) - .....................
etc.
3 个评论
John wick
2019-8-11
Image Analyst
2019-8-11
Well you can't just have indexes within parentheses like (:,44), because how could MATLAB possibly know which matrix you're referring to.
John wick
2019-8-11
类别
在 帮助中心 和 File Exchange 中查找有关 Matrix Indexing 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
