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A How do i perform differentiation over summation?

  1. Dec 26, 2016 #1
    upload_2016-12-27_0-33-35.png
     
    Last edited: Dec 26, 2016
  2. jcsd
  3. Dec 26, 2016 #2

    Stephen Tashi

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    It isn't clear what you mean by ##\frac{d}{dx} y##. Are you differentiating a vector ##y## with respect to to another vector ##x## ? (If so, how do you define that sort of derivative?) Or are you differentiating a vector of functions of the scalar variable ##x## with respect to ##x## ?

    You say that ##x## has exactly N samples. If ##x## is vector of constants, I don't what you would mean by differentiating with respect to ##x##. If you have some function ##f(x)## and some set of constants ## c_1,c_2,...## you can talk about forming the derivatives ## f'(c_1), f'(c_2),....##.
     
  4. Dec 26, 2016 #3
    Thank you so much for your reply,
    You are right, here x is a vector and H is a matrix, and i want to differentiate Hx with respect to x

    Here's the complete problem
    upload_2016-12-27_1-2-7.png

    that's how far i have gone, probably it's wrong.
     

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  5. Dec 27, 2016 #4
    upload_2016-12-27_1-2-7-png.110813.png

    please let me know if it's okay!
    that's how far i have gone, probably it's wrong.
     
  6. Dec 31, 2016 #5

    vela

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    You still haven't explained what ##x## is.
     
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