Recent content by Jimmy Johnson

  1. J

    Backward-wave propagation in Metamaterials?

    Ok so I am currently doing a research project on reconfigurable polarization sensitive metamaterials. Namely trying to manually control/determine where electrical and magnetic resonance within the structure will occur dependent on geometrical parameters, so it can then be used with some active...
  2. J

    Standard form, vertex form. Something isn't right here

    In most cases of this topic I've seen in textbooks or online the standard form of a quadratic function is expressed in vertex form. However I agree that it is inconsistent throughout different teachings etc. "Different textbooks have different interpretations of the reference "standard form"...
  3. J

    Standard form, vertex form. Something isn't right here

    An equation can be expressed in standard or vertex form. A quadratic function in standard form is f(x) = a(x - h)2 + k. It's just semantics really, albeit confusingly laid out above. The standard and vertex equations ( y =) are referred to as standard and vertex respectively and in that sense...
  4. J

    Standard form, vertex form. Something isn't right here

    The standard form is expressed by completing the square. The vertex is simply the point on the parabola where the graph changes direction, as shown on the graph you posted above, the (h,k) coordinate which is determined from the vertex form equation (complete the square equation of the function).
  5. J

    Number of complex calculations in FFT and inverse FFT

    What is the O on that scale equation? The calculation is the circular convolution of the x1(t) and x2(t) through ifft(fftx1padded)*(fftx2padded), so the padding was adding zeroes to the vector so that it was the same length and therefore achievable in matlab? after convolution a length 8 was...
  6. J

    Number of complex calculations in FFT and inverse FFT

    Homework Statement Calculate the total number of compex multiplications required for the calculation in (b) when FFTs are used to perform the Discrete Fourier Transforms and Inverse Discrete Fourier Transforms.[/B] There were two FFT multiplied together and one inverse FFT of that product to...
  7. J

    Mathematical proof for non linear system

    Homework Statement Consider the continuous-time processing system in figure 1, which has two inputs and one output. The linear sub-system H is characterised by the impulse response h(t) = e −2t , where t denotes time. Block diagram is the product of x1(t) and x2(t) going through a block step...
  8. J

    Trig Function Help: Get Answers Now

    You had the method right. Find the reference triangle then using toa soh cah find the sine, cosine or tan values to be substituted into the given identity. You might find this link useful...
  9. J

    Trig Function Help: Get Answers Now

    Well that may have been useful information at the start... you have cot = -5/4, find what tan is then recall tan = sin/cos ... or recall cot = cos/sin...
  10. J

    Trig Function Help: Get Answers Now

    Are you forbidden from using a calculator?
  11. J

    Trig Function Help: Get Answers Now

    If you're simply trying to find t, then use cot = 1/tan... If you have a value for t why do you need to use the double angle identities?
  12. J

    2nd order resonance filter amplitude response(z-parameters)

    Thanks again man! You're awesome! appreciate it! And a lot of typos I forgot pretty much all the x's and y's haha
  13. J

    Trig Function Help: Get Answers Now

    Can you give the entire problem?
  14. J

    2nd order resonance filter amplitude response(z-parameters)

    Out of curiosity would you happen to know about the difference equation? More specifically what impact the cosine would have on the difference equation as a coefficient? I know H(z) = Y(z)/X(z), and I separate that to Y(z)*denominator = X(z)*numerator, then take the inverse z transform, would...
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