using f(end)

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HAAAAH 2019-9-5

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评论： Steven Lord 2019-9-5

i am training now for matlab. but i can not understand how matlab works for this one f(end)?

x = [2 5 3]

f = 2

f(x) = f(end) * x

the ans is : f = [2 4 6 0 10]

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Stephen23 2019-9-5

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编辑：Stephen23 2019-9-5

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When used as an index, end returns the last index (for the specific dimension, or as a linear index).

Because f is defined as a scalar in your example, f(end) is simply equal to f, so your example is trivially equivalent to:

x = [2 5 3]
f = 2 
f(x) = f * x

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Guillaume 2019-9-5

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And be aware that Madhan has shown you one possible way to define a function f of x. Although, I wouldn't use the last line as is as it overwrite the function with the result

x = [2, 5, 3];
f = @(x) 2*x;  %note that the variable name here doesn't have to be x. It's not the same x as the 1st line
y = f(x)

Steven Lord 2019-9-5

Because f is defined as a scalar in your example, f(end) is simply equal to f,

I would phrase this slightly differently. Because f has only 1 element, f(end) is f(1). If f had 2 elements, f(end) would be f(2). My hope is that this would make apparent the link between the end index's value and the number of elements in f.

It also generalizes: if f has 5 rows, f(end, 1) is f(5, 1). If f has 7 columns, f(3:4, end) is f(3:4, 7) and f(4, end-1) is f(4, 7-1). Just replace end with the size of f in the corresponding dimension.

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