what does "^" and ".^" difference ?

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Muhammad Faqih
Muhammad Faqih 2019-9-27
回答： Cam 2019-9-27
surely "^" and ".^" had difference in their using. but what exactly they does?

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Walter Roberson
Walter Roberson 2019-9-27
>> [1 2;3 4]^2
ans =
7 10
15 22
>> [1 2;3 4].^2
ans =
1 4
9 16
>> [1 2; 3 4]*[1 2; 3 4] %same as ^2
ans =
7 10
15 22
>> [1 2; 3 4].*[1 2;3 4] %same as .^2
ans =
1 4
9 16
The formal names of the operations are mpower (^) and power (.^) . ^ is for matrix multiplication repeated, where .^ is for element-by-element multiplication repeatedly.

更多回答（1 个）

Cam
Cam 2019-9-27
The dot is a element wise operator, this means that each element is operated on by the element of the same index when you use this. The other "^" will raise any value (scalar, or matrix) to the power of it. A bit difficult to explain in words here is an example:
a = [1 2;3 4]
b = [2 2;2 2]
a.^b = [1 4;9 16]
As you can see it went element by element and applied the operator. 1^2, 2^2; 2^3, 2^4
In contrast if you do:
a = [1 2;3 4]
b = [2 2;2 2]
a^b = %ERROR must be a scalar
a^2 = [1 4;9 16]
The dot is more applicable to other operators like multiplication and division its less used but still often needed as matlab always assumes matricies are being used first.

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