matrix-inverse

Ways around pinv([inf])=NaN in Octave/Matlab

由 蹲街弑〆低调 提交于 2019-12-11 08:07:18
问题 I am using Octave 3.8.1, a Matlab-like program. I'd like to generalize 1/x to the case where x may be a scalar or a matrix. Replacing 1/x with inv(x) or pinv(x) works for most x , except: octave:1> 1/inf ans = 0 octave:2> pinv([inf]) ans = NaN octave:3> inv([inf]) warning: inverse: matrix singular to machine precision, rcond = 0 ans = Inf Should I convert NaN to 0 afterwards to get this to work? Or have I missed something? Thanks! 回答1: The Moore–Penrose pseudo inverse, which is the basis for

Why is Matlab's inv slow and inaccurate?

由 纵然是瞬间 提交于 2019-12-11 03:58:15
问题 I read at a few places (in the doc and in this blog post : http://blogs.mathworks.com/loren/2007/05/16/purpose-of-inv/ ) that the use of inv in Matlab is not recommended because it is slow and inaccurate. I am trying to find the reason of this inaccuracy. As of now, Google did not give m interesting result, so I thought someone here could guide me. Thanks ! 回答1: The inaccuracy I mentioned is with the method INV, not MATLAB's implementation of it. You should be using QR, LU, or other methods

PHP inverse of a matrix

由 我们两清 提交于 2019-12-10 18:16:25
问题 I saw this question,and pop up this idea. Is there an efficient way to do this in PHP? EDIT Best with a demo? 回答1: You could use the pear package Math_Matrix for this. 回答2: This package claims to be able to do what you are looking for. 回答3: /** * matrix_inverse * * Matrix Inverse * Guass-Jordan Elimination Method * Reduced Row Eshelon Form (RREF) * * In linear algebra an n-by-n (square) matrix A is called invertible (some * authors use nonsingular or nondegenerate) if there exists an n-by-n

Javascript matrix inversion

由 天大地大妈咪最大 提交于 2019-12-09 06:09:26
I am creating a javascript code for matrix inversion.But the function doesn't seem to run. I want my inverted matrix to be displayed where the input matrix was.I have tried alerting values of the invertedMatrix instead of putting them into s but that didn't work either.Would be grateful for any help html <div id = "table3"> <div class = "header">Macierz odwrotna [2x2]</div> <form id = "row1"> <input type = "text" class = "det2"/><!--first row--> <input type = "text" class = "det2"/> </form> <form id = "row2"> <input type = "text" class = "det2"/><!--second row--> <input type = "text" class =

Why is the output of inv() and pinv() not equal in Matlab and Octave?

由 孤街醉人 提交于 2019-12-09 03:29:11
问题 I have noticed that if A is a NxN matrix and it has the inverse matrix. But what the inv() and pinv() function output is different. - My environment is Win7x64 SP1, Matlab R2012a, Cygwin Octave 3.6.4, FreeMat 4.2 Have a look at the examples from Octave: A = rand(3,3) A = 0.185987 0.192125 0.046346 0.140710 0.351007 0.236889 0.155899 0.107302 0.300623 pinv(A) == inv(A) ans = 0 0 0 0 0 0 0 0 0 It's all the same ans result by running the same command above in Matlab. And I calculate inv(A)*A or

Can Spark and the ScalaNLP library Breeze be used together?

由 时光总嘲笑我的痴心妄想 提交于 2019-12-08 15:29:38
I'm developing a Scala-based extreme learning machine, in Apache Spark. My model has to be a Spark Estimator and use the Spark framework in order to fit into the machine learning pipeline. Does anyone know if Breeze can be used in tandem with Spark? All of my data is in Spark data frames and conceivably I could import it using Breeze, use Breeze DenseVectors as the data structure then convert to a DataFrame for the Estimator part. The advantage of Breeze is that it has a function pinv for the Moore-Penrose pseudo-inverse, which is an inverse for a non-square matrix. There is no equivalent

Matlab inverse operation and warning

由 不羁的心 提交于 2019-12-08 08:27:29
Not quite sure what this means. "Warning: Matrix is singular to working precision." I have a 3x4 matrix called matrix bestM matrix Q is 3x3 of bestM and matrix m is the last column of bestM I would like to do C = -Inverse matrix of Q * matrix m and I get that warning and C =[Inf Inf Inf] which isn't right because i am calculating for the camera center in the world bestM = [-0.0031 -0.0002 0.0005 0.9788; -0.0003 -0.0006 0.0028 0.2047; -0.0000 -0.0000 0.0000 0.0013]; Q = bestM(1:3,1:3); m = bestM(:,4); X = inv(Q); C = -X*m; disp(C); A singular matrix can be thought of as the matrix equivalent of

Can Spark and the ScalaNLP library Breeze be used together?

由 ￣綄美尐妖づ 提交于 2019-12-08 07:52:27
问题 I'm developing a Scala-based extreme learning machine, in Apache Spark. My model has to be a Spark Estimator and use the Spark framework in order to fit into the machine learning pipeline. Does anyone know if Breeze can be used in tandem with Spark? All of my data is in Spark data frames and conceivably I could import it using Breeze, use Breeze DenseVectors as the data structure then convert to a DataFrame for the Estimator part. The advantage of Breeze is that it has a function pinv for the

Matlab inverse operation and warning

由 拥有回忆 提交于 2019-12-08 06:33:33
问题 Not quite sure what this means. "Warning: Matrix is singular to working precision." I have a 3x4 matrix called matrix bestM matrix Q is 3x3 of bestM and matrix m is the last column of bestM I would like to do C = -Inverse matrix of Q * matrix m and I get that warning and C =[Inf Inf Inf] which isn't right because i am calculating for the camera center in the world bestM = [-0.0031 -0.0002 0.0005 0.9788; -0.0003 -0.0006 0.0028 0.2047; -0.0000 -0.0000 0.0000 0.0013]; Q = bestM(1:3,1:3); m =

Good matrix inversion routines in C

由 天涯浪子 提交于 2019-12-08 02:27:00
问题 As part of a python code for a numerical calculation, I must invert somewhat large (sparse) matrices (~100x100) many times. I would really like to speed up the program, and one of the ways suggested to me is to call to a subroutine in C for the matrix inversion step. Are there any recommended efficient and well-tested C routines for this task? Thank you. 回答1: >>> from numpy import * >>> from numpy.linalg import inv >>> from scipy.sparse import csr_matrix >>> m = matrix([[3,1,5],[1,0,8],[2,1,4
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