vector function takes vector input ?

Hello !

I am having truble inserting vectors as an input to a function that is a vector

what I did is

I defined a function as

gradient=@(x) [1;x;x^2;x^3];

then I need to input a vector to it. like this

gradient([2 ;3 ; 4])

or

gradient([2  3  4])

so the result I am hoping for is a matrix where each column represent a function (1,x,x^2,x^3)

and each row is the value of the function at each point in the input vector.

so it would be some thing like:

1 2 4 8

1 3 9 27

1 4 16 46

I have done this using loop. but since the data I am dealing with is large this takes so long and I would brefer a method that does it in a vector form.

Answer 1

[Star Strider]

First, gradient is a quite useful built-in MATLAB function, so name your function something different.

Second, your function needs some help.

Try this:

myGradient = @(x) [ones(size(x(:))), x(:), x(:).^2, x(:).^3];
Y = myGradient([2 3 4])

I will leave it to you to explore the details of colon operator single-indexing (it forces ‘x’ here to be a column vector), and the necessity to use the ones function.

Y =
     1     2     4     8
     1     3     9    27
     1     4    16    64

[Nora Khaled]

Thank you very much !

this worked very well and way much faster that my original loop.

[Star Strider]

My pleasure!

If my Answer helped you solve your problem, please Accept it!

[Nora Khaled]

sorry did not know I had a choice of accepting the answer.

And again, Thank you!

[Star Strider]

As always, my pleasure.

Thank you!