Why am I not getting an array when using inverse tangent on an array in MATLAB?

[Link-]

Hi guys,

I am having a problem here with a MATLAB m.file, I am trying to take the inverse tangent of an array and expect from this function to get another array, but for some reason I don't get an array just a single number.

Any MATLAB guru that could help me with this problem?

Thanks
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[Dr Transport]

arctan isn't an intrinsic matrix function. You have to calculate each element sparately.

 

[Link-]

arctan isn't an intrinsic matrix function. You have to calculate each element sparately.

Thanks for the help

 

[belliott4488]

arctan is not a built-in Matlab function, but atan(x) and atan2(x,y) both are, and they both take arrays for input arguments.

 

[Link-]

arctan is not a built-in Matlab function, but atan(x) and atan2(x,y) both are, and they both take arrays for input arguments.

Really? Because my input was an array an I just got a single number, not an array. There's something that I could do to get an array?

 

[belliott4488]

Really? Because my input was an array an I just got a single number, not an array. There's something that I could do to get an array?

Your input for which function? As I said, arctan is not built-in, so I can't guess how it would behave; that would depend on how it was written.

Here are simple examples of the other two:

>> theta = atan([.1 .2 .3 .4])

theta =

    0.0997    0.1974    0.2915    0.3805

>> theta = atan2([1 2 3 4],[10 10 10 10])

theta =

    0.0997    0.1974    0.2915    0.3805

 

[Link-]

I use atan(), common I would notice if is not a built in function.

My array was stored on a variable then I tried to take the atan of the variable an expected an array.

 

[belliott4488]

I use atan(), common I would notice if is not a built in function.

I don't understand this sentence.

Are you asking how to tell if a function is built-in? Use "which", as in

>> which atan

which will return the location of the function's m-file, or it might simply say that the function is a pre-compiled function, i.e. it has no m-file.

My array was stored on a variable then I tried to take the atan of the variable an expected an array.

You should get back an array of the same dimensions, as in this example:

>> M = [.1 .2 .3
        .4 .5 .6 ];
>> atan(M)

ans =

    0.0997    0.1974    0.2915
    0.3805    0.4636    0.5404

 

[Link-]

I ran again the m-file and got the array I was looking for, maybe one of my inputs were wrong.

By that sentence that I wrote, sorry... for some reason my English is getting worse. What I tried to say is that I used atan() and not arctan, that will note by the "? Undefined command/function 'arctan'" message that is not a MATLAB function.

Thanks for the help belliott4488

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