Recent content by Ethers0n

  1. E

    Need help with proof of sets of integers

    ok so it's not really a proof by contradiction then. is it still sufficient though? I still feel like the wording could be better.
  2. E

    Probability and Expected value

    :P yes I could add that up, but I tend to leave things written out like that so that I can quickly see where I got it from (to double check my work) thank you!
  3. E

    Need help with proof of sets of integers

    how does this sound? there is a set S with three elements that are integers. Assume that any two of these elements are added together and always produce an odd value. (ie x1+x2 or x1+x3 or x2+x3 is always odd). assuming that all three elements of S have even values, take the sum of any two...
  4. E

    Probability and Expected value

    ah, it looks like I switched those. .25*[(13+12+11+...+2+1)/13)]*2 + .25*[(13+12+11+...+2+1)/13)]*.5 + .5*[(13+12+11+...+2+1)/13)]-15] is this correct then?
  5. E

    Need help with proof of sets of integers

    1.From the problem statement Let Z+ be the set of all positive integers; that is, Z+ = {1,2,3,...} Define Z+ x Z+ = {(a1, a2) : a1 is an element of Z+ and a2 is an element of Z+ } 2. If S is contained in Z+ and |S| >=3, prove that there exist distinct x,y that are elements of S such...
  6. E

    Probability and Expected value

    so the probability of drawing a heart or a diamond is 1/4 the probability of drawing a black card is 1/2 The expected value once a heart is drawn is [(13+12+11+...+2+1)/13)]*2 The '*2' because of the problem definition. The expected value once a diamond is drawn is [(13+12+11+...+2+1)/13)]...
  7. E

    Non Homogeneous Recurrence Relation

    well, if I sub in bm = (n+1)an into the original equation of (n+2)an+1 = 2(n+1)an+2n I get bm+1=2bm+2m (1) bm+1-2bm=2m (2) bm-2bm-1=2m-1 (3) 2bm-4bm-1=2m (1)-(3) (4) bm+1-4bm+4bm-1=0 (5) bm-4bm-1+4bm-2=0 (6) r2-4r+4=0 (7) (r-2)(r-2)=0 (8) bm= c12m+c2m2m but I don't really know...
  8. E

    Non Homogeneous Recurrence Relation

    1. solve the following recurrence relation for an 2. (n+2)an+1= 2(n+1)an+2^{n}, n>=0, a0=1 I shifted the index, multiplied through by the 2^{n} term and then subtracted the resulting equation from the original equation to get rid of the 2^{n} term... 3. I have gotten to this point...
  9. E

    Probability and Expected value

    This is for a discrete math homework set. 1. Suppose the cards in a deck are given the following values: Ace has value 1, two has value 2,..., ten has value 10, Jack has value 11, Queen has value 12, and King has value 13. A player selects a card. If it is a heart, the player receives half...
  10. E

    MATLAB Designing a Transfer Function in MATLAB for Servo Motor Control

    sorry, that's suppossed to be B(z)/A(z) = D darn formatting...
  11. E

    MATLAB Designing a Transfer Function in MATLAB for Servo Motor Control

    This post is cross listed at the below url https://www.physicsforums.com/showthread.php?t=73985 I'm attempting to use MATLAB to solve an electrical engineering problem dealing with controls... I'm trying to design a transfer function which will control a servo motor using what is often...
  12. E

    Understanding Wave Graphs: 4t & 30° Phase Angle

    Well, I may be very wrong, but the angle is the phase angle of the sinusoid. This comes into play when dealing with power factors. ie, phase matching. hope this sheds some light... (take everything with a grain of salt, it tastes better that way)
  13. E

    MATLAB Controller Designed in Matlab is blowing up

    Well, that's the problem, that transfer function is meant to be stable...i realize that it's not, but am unsure as to how why it's proving unstable. As I understand it, this method is supossed to return a stable controller transfer function. Am I wrong in this assumption? Or is the code...
  14. E

    MATLAB Controller Designed in Matlab is blowing up

    I've been having some trouble figuring out why a controller that I've designed using MATLAB is giving me trouble. I"m using a polynomial equations approach to the design problem. It seems that the Z transform of the controller's transfer function has near zero values in the numerator. I'm not...
  15. E

    MATLAB Pull Value from MATLab Matrix: Solve the Problem

    Does anyone know how to pull the value of an element which has been calculated and placed in a matrix out of the matrix? ie. M = [a1, a2; b1, b2]; c = a1*3; ? I can't seem to find any information online... Thanks.
Back
Top