comtech.usa's articles:

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How to solve Reigh Quotient type problem? 6 30 (4/19/2012 2:33:03 PM) comp.soft-sys.matlab How to solve Reigh Quotient type problem? max (w+w0)'*C*(w+w0) s.t w'*w=1 where w0 is given. Thank you! ... Lucy

How to find all roots of this high order polynomial equation? 7 35 (4/19/2012 3:47:02 AM) comp.soft-sys.matlab Hi all, I need to find all real $u$'s, such that $$\sum_{i=1}^{n}{\left(\frac{w_{i}}{u-e_{i}}\right)^{2}}=1$$ where $$\sum_{i=1}^{n}{w_{i}^2}=1$$ and w_{i}'s and e_{i}'s are given. My questions are: are the... Lu

How to solve this univariate equation? Thank you! 5 27 (4/18/2012 5:07:14 PM) comp.soft-sys.matlab I have sum(w_i, i from 1 to n)=1 given, and also I am given a set of numbers e_i, i from 1 to n. Now I need to find a number u, such that sum(w_i/(u - e_i)^2, i from 1 to n) ... My questions are: are there ... Lucy

How to solve this non-convex quadratically constrained quadratic programming 10 29 (4/18/2012 12:08:39 AM) comp.soft-sys.matlab How to solve this quadratically constrained quadratic programming problem? Hi all, Could you please shed some lights on this? (Not a homework problem) I am looking for solutions to solve the following proble... Lucy

could anybody please show how to use Kalman filter to do simple forecasting? 1 77 (1/13/2012 5:40:55 PM) comp.soft-sys.matlab Hi all, I read a bunch of literature on Kalman filter and got very confused... It seems there are hidden states and there are observations... For my simple application, I want to forecast the next step of a ... Lucy

Is there a way to implement 2D filter thru 1D filter? 4 40 (1/11/2012 11:33:33 PM) comp.soft-sys.matlab Hi all, I am trying to figure out if there is a way to do meaningful 2D filtering thru 1D filter functions... Assuming we don't have 2D filters in Matlab and I only have 1D filters in Matlab. How can I achie... Lucy

How do I fit data to multiple seasonality ARIMA in Matlab 2 52 (12/12/2011 5:28:37 PM) comp.soft-sys.matlab Hi all, Could you please help me? I am looking for ways to fit data to ARIMA model with multiple seasonalities in Matlab, using the Econometric toolbox. Thanks a lot! ... Lucy

Pointer to STL element address? 17 20 (5/25/2009 3:21:51 PM) comp.lang.c++ Hi all, In the following STL insertion, how do I maintain a pointer pointing to the address of that element being inserted? Thanks! my_list.push_back(my_element); my_map[key]=my_element; ... Michael

how to efficiently find the difference of two times in C++? 7 31 (5/25/2009 4:12:33 AM) comp.lang.c++ Dear all, I have the time data of the following formats: How do I take their difference accurately in C++? 2009-03-09 04:07:39.017404079 2009-03-09 04:07:55.587754011 Thanks! ... Michael

SOS! how do I put date strings on x-axis? 5 29 (2/25/2009 4:22:28 PM) comp.soft-sys.matlab Hi all, This is urgent and I am running for a presentation. How do I put date strings on x-axis? Each data point is indeed associated with a date-string (collected on that date, however the dates are not uni... Lucy

comtech.usa's replies:

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Need reference about the derivatives of Direc Delta function... 9 12 (8/18/2006 12:30:28 AM) comp.dsp Specificly, I need to find the function values of the nth derivative of Direc Delta function. What is the value of DDelta_n_(c), where c is not zero? Is this value zero? (Here DDelta_n_(x) means the nth deri... comtech.usa (46)

finding the coefficient of the nth term in a power series? 5 37 (8/22/2006 9:51:01 PM) comp.soft-sys.matlab Hi all, Is it possible to write out in closed-form the coefficient of the n-th term in the power series expansion of the following: (1-a1*x - a2*x^2- a3*x^3- ... - a_k*x^k)^(-p), where p is a positive real n... comtech.usa (46)

help! I have difficulty finding the Fourier transform 6 31 (7/20/2008 4:40:40 AM) comp.dsp Hi, I have difficulty in taking fourier transform of a function f(t). The function f(t) is not integrable. Through analytical analysis, f(t) behaves asymptotically the same as a*log(t)/t for t-> +infinity; a... lunamoonmoon (258)

best way to approximating a non-smooth function using polynomials... 21 42 (2/13/2009 5:46:04 PM) comp.dsp Hi all, Suppose I am looking at a non-smooth function which is max(x - c, 0), is there a way to approximate it by polynomials of x or other functionals of x? Of course, Taylor expansion may have some troubl... lunamoonmoon (258)

SOS! how do I put date strings on x-axis? 5 29 (2/25/2009 4:22:28 PM) comp.soft-sys.matlab Hi all, This is urgent and I am running for a presentation. How do I put date strings on x-axis? Each data point is indeed associated with a date-string (collected on that date, however the dates are not uni... comtech.usa (46)

how to efficiently find the difference of two times in C++? 7 31 (5/25/2009 4:12:33 AM) comp.lang.c++ Dear all, I have the time data of the following formats: How do I take their difference accurately in C++? 2009-03-09 04:07:39.017404079 2009-03-09 04:07:55.587754011 Thanks! ... comtech.usa (46)

Pointer to STL element address? 17 20 (5/25/2009 3:21:51 PM) comp.lang.c++ Hi all, In the following STL insertion, how do I maintain a pointer pointing to the address of that element being inserted? Thanks! my_list.push_back(my_element); my_map[key]=my_element; ... comtech.usa (46)

Is there a way to implement 2D filter thru 1D filter? 4 40 (1/11/2012 11:33:33 PM) comp.soft-sys.matlab Hi all, I am trying to figure out if there is a way to do meaningful 2D filtering thru 1D filter functions... Assuming we don't have 2D filters in Matlab and I only have 1D filters in Matlab. How can I achie... comtech.usa (46)

How to solve this non-convex quadratically constrained quadratic programming 10 29 (4/18/2012 12:08:39 AM) comp.soft-sys.matlab How to solve this quadratically constrained quadratic programming problem? Hi all, Could you please shed some lights on this? (Not a homework problem) I am looking for solutions to solve the following proble... comtech.usa (46)

How to solve this univariate equation? Thank you! 5 27 (4/18/2012 5:07:14 PM) comp.soft-sys.matlab I have sum(w_i, i from 1 to n)=1 given, and also I am given a set of numbers e_i, i from 1 to n. Now I need to find a number u, such that sum(w_i/(u - e_i)^2, i from 1 to n) ... My questions are: are there ... comtech.usa (46)