Convert formula into coding form

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Syakira Akmal 2017-4-1

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回答： Image Analyst 2017-4-1

Hi, i don't know how to convert formula into coding form. Example of formula

theta(kx, ky) = arctan(dy/dx)

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Answer 1

Star Strider 2017-4-1

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The arguments to the function do not match the arguments to the arctangent function. Are ‘kx’ and ‘ky’ the same as ‘dx’ and ‘dy’ or different?

One of these should do what you want:

theta = @(kx, ky) atan2(ky,kx);                             % The Values (Or Vectors) Themselves
theta = @(kx, ky) atan2(gradient(ky),gradient(kx));         % The Derivatives Of The Vectors

The atan2 function puts the returned angles in the correct quadrants. The atan function does not.

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Syakira Akmal 2017-4-1

(kx, ky) is a point. dy = In(kx,ky+1) - In(kx,ky-1) dx = In(kx+1,ky) - In(kx-1,ky)

Star Strider 2017-4-1

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My function then changes to:

theta = @(kx, ky) atan2(In(kx,ky+1) - In(kx,ky-1), In(kx+1,ky) - In(kx-1,ky));  % Directly Using ‘In’

That should work.

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Answer 2

John D'Errico 2017-4-1

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编辑：John D'Errico 2017-4-1

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I'd strongly suggest that you start reading the getting started tutorials. This is a very basic question, although I honestly have no idea what it is that you really want to do here. If I had to guess, you need to learn how to write a function.

Using a four quadrant atan, this would do what you want.

theta = @(kx,ky) = atan2(ky,kx);

Or do this:

theta = @(kx,ky) = atan(ky/kx);