svd | Python code implementing the power method | Machine Learning library
kandi X-RAY | svd Summary
kandi X-RAY | svd Summary
An implementation of the greedy algorithm for SVD, using the power method for the 1-dimensional case. For the post Singular Value Decomposition Part 2: Theorem, Proof, Algorithm. And the first (motivational) post in the series: Singular Value Decomposition Part 1: Perspectives on Linear Algebra.
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svd Key Features
svd Examples and Code Snippets
def svd(tensor, full_matrices=False, compute_uv=True, name=None):
r"""Computes the singular value decompositions of one or more matrices.
Computes the SVD of each inner matrix in `tensor` such that
`tensor[..., :, :] = u[..., :, :] * diag(s[..
def svd(a, max_iter, epsilon, precision_config=None):
precision_config_proto = ""
if precision_config:
precision_config_proto = precision_config.SerializeToString()
return gen_xla_ops.xla_svd(a, max_iter, epsilon, precision_config_proto)
Community Discussions
Trending Discussions on svd
QUESTION
I just got my new MacBook Pro with M1 Max chip and am setting up Python. I've tried several combinational settings to test speed - now I'm quite confused. First put my questions here:
- Why python run natively on M1 Max is greatly (~100%) slower than on my old MacBook Pro 2016 with Intel i5?
- On M1 Max, why there isn't significant speed difference between native run (by miniforge) and run via Rosetta (by anaconda) - which is supposed to be slower ~20%?
- On M1 Max and native run, why there isn't significant speed difference between conda installed Numpy and TensorFlow installed Numpy - which is supposed to be faster?
- On M1 Max, why run in PyCharm IDE is constantly slower ~20% than run from terminal, which doesn't happen on my old Intel Mac.
Evidence supporting my questions is as follows:
Here are the settings I've tried:
1. Python installed by
- Miniforge-arm64, so that python is natively run on M1 Max Chip. (Check from Activity Monitor,
Kind
of python process isApple
). - Anaconda. Then python is run via Rosseta. (Check from Activity Monitor,
Kind
of python process isIntel
).
2. Numpy installed by
conda install numpy
: numpy from original conda-forge channel, or pre-installed with anaconda.- Apple-TensorFlow: with python installed by miniforge, I directly install tensorflow, and numpy will also be installed. It's said that, numpy installed in this way is optimized for Apple M1 and will be faster. Here is the installation commands:
ANSWER
Answered 2021-Dec-06 at 05:53Since the benchmark is running linear algebra routines, what is likely being tested here are the BLAS implementations. A default Anaconda distribution for osx-64 platform is going to come with Intel's MKL implementation; the osx-arm64 platform only has the generic Netlib BLAS and the OpenBLAS implementation options.
For me (MacOS w/ Intel i9), I get the following benchmark results:
BLAS Implmentation Mean Timing (s)mkl
0.95932
blis
1.72059
openblas
2.17023
netlib
5.72782
So, I suspect the old MBP had MKL installed, and the M1 system is installing either Netlib or OpenBLAS. Maybe try figuring out whether Netlib or OpenBLAS are faster on M1, and keep the faster one.
Specifying BLAS ImplementationHere are specifically the different environments I tested:
QUESTION
I've mostly worked with MATLAB, and I am converting some of my code that I have written into Python. I am running into an issue where I have a boolean mask that I am calling Omega, and when I apply the mask to different m by n matrices that I call X and M I get different objects. Here is my code
...ANSWER
Answered 2022-Mar-21 at 22:12M
is a np.matrix
, which are always 2-D (so it has two dimensions). As the error message indicates, you can only use a 0- or 1-D array when assigning to an array masked with a boolean mask (which is what you're doing).
Instead, convert M
to an array first (which, as @hpaulj pointed out, is better than using asarray
+ ravel
)
QUESTION
I am following the example of eigen decomposition from here, https://github.com/NVIDIA/CUDALibrarySamples/blob/master/cuSOLVER/syevd/cusolver_syevd_example.cu
I need to do it for Hermatian complex matrix. The problem is the eigen vector is not matching at all with the result with Matlab result.
Does anyone have any idea about it why this mismatch is happening?
I have also tried cusolverdn svd method to get eigen values and vector that is giving another result.
My code is here for convenience,
...ANSWER
Answered 2022-Mar-04 at 16:07Please follow the post for the clear answer, https://forums.developer.nvidia.com/t/eigen-decomposition-of-hermitian-matrix-using-cusolver-does-not-match-the-result-with-matlab/204157
The theory tells, A*V-lamda*V=0
should satisfy, however it might not be perfect zero. My thinking was it will very very close to zero or e-14
somethng like this. If the equation gives a value close to zero then it is acceptable.
There are different algorithms for solving eigen decomposition, like Jacobi algorithm, Cholesky factorization... The program I provided in my post uses the function cusolverDnCheevd
which is based on LAPACK
. LAPACK
doc tells that it uses divide and conquer algorithm
to solve Hermitian matrix. Here is the link, http://www.netlib.org/lapack/explore-html/d9/de3/group__complex_h_eeigen_ga6084b0819f9642f0db26257e8a3ebd42.html#ga6084b0819f9642f0db26257e8a3ebd42
QUESTION
I want to generate a rank 5 100x600 matrix in numpy with all the entries sampled from np.random.uniform(0, 20), so that all the entries will be uniformly distributed between [0, 20). What will be the best way to do so in python?
I see there is an SVD-inspired way to do so here (https://math.stackexchange.com/questions/3567510/how-to-generate-a-rank-r-matrix-with-entries-uniform), but I am not sure how to code it up. I am looking for a working example of this SVD-inspired way to get uniformly distributed entries.
I have actually managed to code up a rank 5 100x100 matrix by vertically stacking five 20x100 rank 1 matrices, then shuffling the vertical indices. However, the resulting 100x100 matrix does not have uniformly distributed entries [0, 20).
Here is my code (my best attempt):
...ANSWER
Answered 2022-Jan-24 at 15:05Not a perfect solution, I must admit. But it's simple and comes pretty close.
I create 5 vectors that are gonna span the space of the matrix and create random linear combinations to fill the rest of the matrix.
My initial thought was that a trivial solution will be to copy those vectors 20 times.
To improve that, I created linear combinations of them with weights drawn from a uniform distribution, but then the distribution of the entries in the matrix becomes normal because the weighted mean basically causes the central limit theorm to take effect.
A middle point between the trivial approach and the second approach that doesn't work is to use sets of weights that favor one of the vectors over the others. And you can generate these sorts of weight vectors by passing any vector through the softmax function with an appropriately high temperature parameter.
The distribution is almost uniform, but the vectors are still very close to the base vectors. You can play with the temperature parameter to find a sweet spot that suits your purpose.
QUESTION
I have a 3D array with lon(1:144)(range 0-360 with a step of 2.5), lat(1:29) (20-90 with a step of 2.5) and one variable in time (1:180)(30 years containing 6 months per year).
...ANSWER
Answered 2022-Jan-20 at 20:06The problem lies in this line of code modes <- as.data.frame(svd.result$u)
. In order to convert the results back to a 3D array, you need modes
to actually be a matrix rather than a dataframe. Your code should work if you simply change it to modes <- svd.result$u
.
QUESTION
I am using Python to convert a .dat file (which you can find here) to csv in order for me to use it later in numpy or csv reader.
...ANSWER
Answered 2022-Jan-12 at 07:46It seems like your dat file uses Shift JIS
(Japanese) encoding.
So you can pass shift_jis
as the encoding
argument to the open
function.
QUESTION
I'm trying this simple whitening function in python in R
Python
...ANSWER
Answered 2021-Dec-07 at 00:53It is usually written wiki, where V* is the transpose of V:
And this is what you get back in scipy.linalg.svd:
Factorizes the matrix a into two unitary matrices U and Vh, and a 1-D array s of singular values (real, non-negative) such that a == U @ S @ Vh, where S is a suitably shaped matrix of zeros with main diagonal s.
Whereas for svd in R they return you V. Therefore should be:
QUESTION
I want to compute the singular value decomposition of each slice of a 3D matrix.
I used numpy and scipy to compute the SVD, but both of them are significantly slower than the MATLAB implementation. While the numpy and scipy versions take around 7 s, the MATLAB version takes 0.7 s only.
Is there a way to accelerate the SVD computation in Python?
Python
...ANSWER
Answered 2021-Dec-03 at 15:34I'm not certain this fixes your issue, but you don't need to loop anything because np.linalg.svd()
already handles n-dimensional arrays. (Even if it didn't, you basically never need loops in NumPy.)
This is how I'd do what you're doing:
QUESTION
Theoretically, the projection result of PCA and SVD is the same if the feature has mean 0. So I tried it on python.
...ANSWER
Answered 2021-Oct-04 at 07:09From the help page for scaler :
with_mean bool, default=True If True, center the data before scaling. This does not work (and will raise an exception) when attempted on sparse matrices, because centering them entails building a dense matrix which in common use cases is likely to be too large to fit in memory.
For PCA and SVD to give the same output, you need to center and scale the data, see also this post for details, so if you do:
QUESTION
I'm working on an UE4 plugin and want to use the Eigen library. It appears that UE4 has already integrated the library, which you can see in Engine>Source>ThirdParty>Eigen.
I looked at other plugins, such as AlembicImporter, for guidance. To use Eigen, I see that they add "Eigen"
in the build.cs file and write #include
in the source files that use Eigen, where ...
could be either Dense, SVD, Sparse, etc.
I tried this, but when I build my project, I get the error
...ANSWER
Answered 2021-Sep-25 at 16:38Looks like prebuilt UE4 doesn't include the "compiled" Eigen headers ("Dense", "Sparse", etc.), though it does include the Eigen "src" folder.
If you compile your Engine from source, you should have a complete Eigen install in the ThirdParty folder. You can then use that just like various Engine plugins do. But compiling Unreal from source is a bit of a pain and takes a lot of hard drive space. This would also prevent you from distributing your plugin in source form, as normal users wouldn't have Eigen available.
It's probably easiest to include a local copy of Eigen with your plugin - it's just headers, so you can include it with just a private include path in the build.cs.
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