This book provides both insight and answers for those attempting to solve these problems. The subject of sparse matrices has its root in such diverse fields as management science, power systems analysis, surveying, circuit theory, and structural analysis.

## Direct Methods for Sparse Matrices — I. S. Duff, A. M. Erisman, J. K. Reid | Humanitas

This second edition is a complete rewrite of the first edition published 30 years ago. Much has changed since that time.

Problems have grown greatly in size and complexity; nearly all examples in the first edition were of order less than 5, in the first edition, and are often more than a million in the second edition. Computer architectures are now much more complex, requiring new ways of adapting algorithms to parallel environments with memory hierarchies. Because the area is such an important one to all of computational science and engineering, a huge amount of research has been done in the last 30 years, some of it by the authors themselves.

This new research is integrated into the text with a clear explanation of the underlying mathematics and algorithms.

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Al Erisman is the Executive in Residence in the School of Business, Government, and Economics at Seattle Pacific University and is executive editor of Ethix magazine , which he co-founded with a colleague in Over the past 15 years he has lectured on five continents in areas of business, technology, mathematics, ethics, faith, and economic development.

Non-numeric computing techniques havebeen included, as well as frequent illustrations, in an attempt to bridge the usually wide gap between the printed page and the working computer code.

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Despite this practical bias, it is recognized that many aspects of the subject are of interest in their own right, and the book aims to be suitablealso for a student course, probably at M. Exercises have been included to illustrate and strengthen understanding of the material, as well as to extend it. Efficient use of sparsity is a key to solving large problems in many fields. This book will supply both insight and answers for those attempting to solve these problems. Duff , J. It appear Numpy does not support sparse arrays; so I am having to rewrite my code to support the sparse array or expand them and load into a Numpy array.

It is not clear to me how sparse arrays are handled. Does the API expand them and then process or is something else done? Thank you for the great article! Perhaps you have a bug, post on stackoverflow? Perhaps try using a smaller dataset? We convert the text data to sparse matrix using tfIdf vector. Can I just add this sparse matrix to my numerical variables and use it as feature variable data? Yes, you can combine the vectors or use a model that supports two inputs one for text and one for numerical data e. Where a vector can be expressed as the combination of the base of the space vector.

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For example in 3D Euclidean, a vector has 3 coordinates one for each 3d space dimensions. So Sparsity, in a infinity space, where we would need ideally a lot of coordinates infinity , to define completely this vector vs that space base, must be summarize with only few coordinates the main ones , because this vector does not depend of the rest of the base or nearly … Another way of see it is, that sparsity it is a characteristic of reducing dimensions after projecting the vector over an infinite or large space base , because only depend of few of them, that clearly simplifying the complexity … Even we can force via Regularize weights, PCA analysis, search for significative covariances or independent variables , ,etc.

Just in order to retain only the main coordinates… This is a picture that help in case to introduce and the reason to practice with sparsity tools …I hope could help anyone else in the same situation …. Say, a dataset uses a specific nonzero value say , and this value does not appear in original data in stead of zero.

Is there a way around to use the libraries in stead of replacing them with 0 before library calls? I would like to do a simulation study and I need simulate a TFIDF matrix, using some distribution for its components…for instance…diritchlet distribution…. Thanks for sharing.

However, I have a question about the CSR format shown in your example. Hi Jason, great post as many others.

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I am playing with some weird datasets which seems to be composed of quite sparse images avg. Could you point me to an algorithm to determine the region with the highest density of non-zero elements in a sparse matrix? It does not have to be a contiguous sub-matrix of non-zero elements, I have in mind something like k-means but not as computationally heavy. Perhaps something like a max-pool or avg-pool over the dense matrix is my first thought? Can you give me some insight on this matter?

Can someone help me to understand index pointer with following example? It really depends on the specifics of your data. Perhaps experiment with a few approaches and compare results? Found this article by searching sparse matrix to normal matrix, and you make matrices so easy to understand yet with details. Thank you so much! Sorry, I am not familiar with that package. Perhaps try posting on stackoverflow or crossvalidated? Name required. Email will not be published required. Tweet Share Share. Linear Algebra for Deep Learning.

## Direct Methods for Sparse Matrices

Jason Brownlee March 15, at pm. Abdullahi Mohammad March 16, at am. Jason Brownlee March 16, at pm. Nihad Almahrooq March 16, at pm. Jason Brownlee March 17, at am. Like what for example? Great tip, thanks David. Nihad Almahrooq March 17, at pm. Hi Jason and all and its great efforts ur given this fields.

Regards Reply. Jason Brownlee March 18, at am. Are you able to give more context? Tim March 19, at am. Jason Brownlee March 19, at am. I thought sparse arrays could be provided directly to Keras. Have you tried?