kemelmi1's articles:

Items(34) /4 Next >> Last >|

making an evaluation of a VERY long expression much faster 8 13 (7/3/2009 12:10:24 PM) comp.soft-sys.matlab Hello, How can an evaluation of a very very long expression can be made faster. My expression has terms with the operation .* between matrices and then those terms are summed together for example: A.*B + B.*C... kem

spatial finite differences in two dimensions (something like 2 13 (2/20/2009 10:48:25 AM) comp.soft-sys.math.mathematica Hi, Is there a possibility in mathematica to get the coefficients or formula for approximation of spatial derivatives with finite differences. And, to get these formulas also for different orders of appro... kem

a simple question about EulerEquations 0 18 (2/4/2009 10:33:40 AM) comp.soft-sys.math.mathematica Hi, It seems that mathematica gives a different expression for Euler- Lagrange equation. Isn't the answer to: EulerEquations[ f[u'[x],u[x],x] , u[x] , x] should be: Derivative[0, 1, 0][f][Deriv... kem

simplifying a resulted derivative expression 2 15 (2/3/2009 12:17:16 PM) comp.soft-sys.math.mathematica Hi, I have a function f[ux, uy, vx, vy, wx, wy, u, v, w, x, y] I am doing different manipulations with this function and the results I get have expressions like that: Derivative[0, 0, 0, 0, 0, 0, 1, 0, 0... kem

remove higher orders terms from mathemtica's result 2 76 (7/29/2008 10:10:33 AM) comp.soft-sys.math.mathematica Hi, Given this: K = (1+vy) (zx+wx) + vx (zy+wy); Expand[K^2] Is it possible to remove automatically the 3rd and 4th orders from the result of 'Expand[K^2]' ? By 3rd order I mean terms like: 2 wy z... kem

what regularization is used in slash operator on sparse rank deficient matrices? 5 18 (5/12/2008 12:53:38 PM) comp.soft-sys.matlab Hi I use slash to solve the system A x =b and my A is sparse rank deficient matrix. Do you know what kind of regularization is used by matlab? Tikhonov regularization? Thanks ... kem

need explanation: something that works with \ operator doesnt work with lsqnonlin function 0 16 (5/5/2008 6:34:29 PM) comp.soft-sys.matlab Hi, I have a LINEAR problem that I can solve using \ (slash) operator. I need to solve a NON_LINEAR version of this problem. For this I suppose I should use LSQNONLIN. I tried to use it and it doesn't... kem

what is better to use: fmincon OR lsqnonlin 1 105 (5/5/2008 6:21:46 PM) comp.soft-sys.matlab Hi, My objective function is to minimize the L2 norm of some vector + I have a linear constraint on the variables. So the output of the objfun: 1) in case of using lsqnonlin: F = [ f_1 ; f_2 ; ... kem

maximum number of variables to be used with fminunc,lsqnonlin 6 52 (5/1/2008 11:25:54 AM) comp.soft-sys.matlab Hi, What is the maximum number of variables that can be used with fminunc or lsqnonlin functions? In my case these get out of memory for 6000 variables. Does it make sense? Can this be optimized some... kem

nonlinear optimization 1 27 (4/30/2008 3:36:53 PM) comp.soft-sys.matlab Hi, I am trying to solve the following problem using matlab's optimization toolbox. ----------------------------------------------------------------- The problem is: min_z || A(:) - S(:)||^2 ... kem

kemelmi1's replies:

Items(20) /2 Next >> Last >|

open parenthesis and reduce an expression 2 15 (4/17/2007 12:39:35 AM) comp.soft-sys.math.mathematica Hi, How can I reduce the following formula for instance (Cos[b[x,y]] zx[x,y]-Sin[b[x,y]] zy[x,y]) (zxx Cos[b[x,y]]+zyx Cos[b[x,y]]+ zxx Sin[b[x,y]]-zyx Sin[b[x,y]]+bx (Cos[b[x,y]]-Sin[b[x,y]]) zx[x,y]... kemelmi1 (69)

ezsurf 1 15 (9/10/2007 6:15:51 AM) comp.soft-sys.matlab Hi, To show implicit surfaces I am using 'ezsurf' e.g. ezsurf('x^2+y^2') Now I need to plot only one contour of this surface, e.g. x^2+y^2=5 How can I do that? Thanks ... kemelmi1 (69)

invert 'imtransform ' 2 30 (12/5/2007 5:09:32 PM) comp.soft-sys.matlab Hi, How can I invert the operation of imtransform. e.g. im1 = imtransform(im,TFORM,'XData',[1 w],'YData',[1 h]); .....some processing.... now I want to make: im2 = imtransform( *im1*, *TFORM_inverse* ,'XD... kemelmi1 (69)

using Dsolve for equation: y'' + |y|^2y=ay 3 34 (12/20/2007 9:52:19 PM) comp.soft-sys.math.mathematica Hi, Is it possible to use DSolve to solve the equation: y'' + |y|^2 y=ay ? DSolve[y''[x] + Abs[y[x]]^2 y[x] - a y[x] == 0, y[x], x] gives some strange solution with symbols like K$1764^2 thanks... kemelmi1 (69)

the fastest way to find whether sparse large matrix is singular/rank deficient 9 15 (4/15/2008 11:30:34 AM) comp.soft-sys.matlab Hi, What will be the fastest way to find out whether a given matrix (sparse, large,non-square) is singular or rank deficient. I am using svds(A'A,1,0) to get the smallest singular value for now, bu... kemelmi1 (69)

Defining the elements of a Matrix 1 34 (4/30/2008 10:40:36 AM) comp.soft-sys.matlab Hi, Is there a way that I can define the element index (row, column) of a matrix. For example I have the following matrix in descending order a = [50,30,10,1], and I've located the highest value using... Rasha (11)

nonlinear optimization 1 27 (4/30/2008 3:36:53 PM) comp.soft-sys.matlab Hi, I am trying to solve the following problem using matlab's optimization toolbox. ----------------------------------------------------------------- The problem is: min_z || A(:) - S(:)||^2 ... kemelmi1 (69)

maximum number of variables to be used with fminunc,lsqnonlin 6 52 (5/1/2008 11:25:54 AM) comp.soft-sys.matlab Hi, What is the maximum number of variables that can be used with fminunc or lsqnonlin functions? In my case these get out of memory for 6000 variables. Does it make sense? Can this be optimized some... kemelmi1 (69)

what regularization is used in slash operator on sparse rank deficient matrices? 5 18 (5/12/2008 12:53:38 PM) comp.soft-sys.matlab Hi I use slash to solve the system A x =b and my A is sparse rank deficient matrix. Do you know what kind of regularization is used by matlab? Tikhonov regularization? Thanks ... kemelmi1 (69)

making an evaluation of a VERY long expression much faster 8 13 (7/3/2009 12:10:24 PM) comp.soft-sys.matlab Hello, How can an evaluation of a very very long expression can be made faster. My expression has terms with the operation .* between matrices and then those terms are summed together for example: A.*B + B.*C... kemelmi1 (69)