singular


Return elements of the Groebner Basis as they are found

安稳与你 提交于 2020-01-22 19:17:11
问题 This question could refer to any computer algebra system which has the ability to compute the Groebner Basis from a set of polynomials (Mathematica, Singular, GAP, Macaulay2, MatLab, etc.). I am working with an overdetermined system of polynomials for which the full groebner basis is too difficult to compute, however it would be valuable for me to be able to print out the groebner basis elements as they are found so that I may know if a particular polynomial is in the groebner basis. Is there

Return elements of the Groebner Basis as they are found

ⅰ亾dé卋堺 提交于 2020-01-22 19:16:10
问题 This question could refer to any computer algebra system which has the ability to compute the Groebner Basis from a set of polynomials (Mathematica, Singular, GAP, Macaulay2, MatLab, etc.). I am working with an overdetermined system of polynomials for which the full groebner basis is too difficult to compute, however it would be valuable for me to be able to print out the groebner basis elements as they are found so that I may know if a particular polynomial is in the groebner basis. Is there

numpy.linalg.inv returns inverse for a singular matrix

做~自己de王妃 提交于 2020-01-11 09:29:48
问题 The matrix below is singular, and AFAIK attempting to invert it should result in numpy.linalg.linalg.LinAlgError: Singular matrix but instead, I do get some output matrix. Note that output matrix is a non-sensical result, because it has a row of 0's (which is impossible, since an inverse of a matrix should itself be invertible)! Am I missing something here related to floating point precision, or the computation of a pseudoinverse as opposed to a true inverse? $ np.__version__ '1.13.1' $ np

Detecting mulicollinear , or columns that have linear combinations while modelling in Python : LinAlgError

拜拜、爱过 提交于 2019-12-30 04:35:13
问题 I am modelling data for a logit model with 34 dependent variables,and it keep throwing in the singular matrix error , as below -: Traceback (most recent call last): File "<pyshell#1116>", line 1, in <module> test_scores = smf.Logit(m['event'], train_cols,missing='drop').fit() File "/usr/local/lib/python2.7/site-packages/statsmodels-0.5.0-py2.7-linux-i686.egg/statsmodels/discrete/discrete_model.py", line 1186, in fit disp=disp, callback=callback, **kwargs) File "/usr/local/lib/python2.7/site

How to find degenerate rows/columns in a covariance matrix

北慕城南 提交于 2019-12-28 13:36:08
问题 I am using numpy.cov to create a covariance matrix from a dataset of over 400 time series. Using linalg.det gives me a value of zero so matrix is singular. I can use linalg.svd to see that the rank is two less than the number of columns so somewhere in the covariance matrix I have some linear combinations to make the matrix degenerate. I have used corrcoef on the underlying timeseries but no correlation > 0.78 so not obvious there. Can someone suggest a method to determine the location of the

How to solve singular matrices?

▼魔方 西西 提交于 2019-12-25 07:40:52
问题 I need to solve more than thousand matrices in a list. However, I get the error Lapack routine dgesv: system is exactly singular . My problem is that my input data are non singular matrices, but following the calculations I need to do on the matrices some of them get singular. A reproducible example with a subset of my data is however not possible as it would be to long (I tried already). Here a basic example of my problem (A would be a matrix after some calculations and R the next

function switching between singular and plural?

女生的网名这么多〃 提交于 2019-12-20 09:55:38
问题 I'm looking for a function that given a string it switches the string to singular/plural. I need it to work for european languages other than English. Are there any functions that can do the trick? (Given a string to convert and the language?) Thanks 回答1: There is no function built into PHP for this type of operation. There are, however, some tools that you may be able to use to help accomplish your goal. There is an unofficial Google Dictionary API which contains information on plurals. You

Assignment of a Singular Iterator

一世执手 提交于 2019-12-20 04:13:23
问题 A "Singular Iterator" is defined as an: iterators that are not associated with any sequence. A null pointer, as well as a default-constructed pointer (holding an indeterminate value) is singular My question 1 would be: Is a default constructed iterator considered a "Singular Iterator"? Secondly, I have been told here that: Results of most expressions are undefined for singular values; the only exceptions are destroying an iterator that holds a singular value, the assignment of a non-singular

zeroinfl “system is computationally singular” whereas no correlation in predictors

蹲街弑〆低调 提交于 2019-12-11 03:17:32
问题 I am trying to model count data on the number of absence days by worker in a year (dependant variable). I have a set of predictors, including information about workers, about their job, etc..., and most of them are categorical variables. Consequently, there is a large number of coefficient to estimate (83), but as I have more than 600 000 rows, I think it should not be problematic. In addition, I have no missing values in my dataset. My dependant variable contains lot of zero values, so I

solving a singular matrix

假如想象 提交于 2019-12-10 11:29:05
问题 I am trying to write a little unwrapper for meshes. This uses a finite-element-method to solve for minimal linear stress between flattened and the raw surface. At the moment there are some vertices pinned to get a result. Without this the triangles are rotated and translated randomly... But as this pinning isn't necessary for the problem, the better solution would be to directly solve the singular matrix. Petsc does provide some methodes to solve a singular system by providing some

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