denis-bz

Electricity in Germany from coal, wind etc.

Keywords: electricity, Germany, renewable, wind, python, pandas

Purpose: summarize data on electricity sources in Germany from the electricity market site smard.de:

total 502489 GWh  365 days, 2020-07-01 .. 2021-06-30:
                 GWh    %   GW
Braunkohle   96253.2 19.2 11.0

denis-bz

#!/usr/bin/env python3
""" https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus/Daten/Fallzahlen_Kum_Tab.html .xlsx
    -> python pandas read_excel
"""
# sheets, from openpyxl --
#  0    Erlaeuterungen  20 rows  1 cols
#  1    Fälle-Todesfälle-gesamt  509 rows  16384 cols  ?!
#  2    BL_7-Tage-Fallzahlen (fixiert)  39 rows  396 cols
#  3    BL_7-Tage-Inzidenz (fixiert)  21 rows  396 cols
#  4    LK_7-Tage-Fallzahlen (fixiert)  419 rows  207 cols

denis-bz

Fitting 1 / x with polynomials in relative error

Keywords, topics: approximation, relative error, inverse, Chebyshev polynomial, Krylov, python

This plot shows polynomials of degrees 10, 15, 20 that fit 1 / x on the range 0.1 .. 2.1, shifted to fits of 1 / (1.1 + x) on -1 .. 1.

denis-bz

A simple matrix with interesting inverse

Keywords: sparse linear solver, python, scipy, testcase, matrix, GMRES, poisson, plot

A simple testcase for GMRES

Wikipedia GMRES says

denis-bz

Mittelmann interior-point and simplex benchmarks from http://plato.asu.edu/bench.html

Keywords, tags: linear programming, benchmark, Mittelmann, HiGHS, python, scipy, sparse-matrix

This plot shows the runtimes of various LP interior-point and simplex programs on Mittelmann's benchmark problems.

To plot similar rows / similar columns near each other,

denis-bz

A few Mittelmann LP benchmarks run with HiGHS-ipm

Keywords, tags: linear programming, benchmark, Mittelmann, HiGHS, python, scipy, sparse-matrix

Here are logfiles for a few of the Mittelmann linear programming benchmark problems, run with the HiGHS interior-point solver via python-scipy. lpbar

denis-bz

#!/usr/bin/env python
""" lpgen34.py LP testcase generator
    d=3: 3n^2 x n^3, 3 1s in each column
        n=55: A 9075 x 166375, 499125 nnz, glpsol simplex 100 minutes
    d=4: 4n^3 x n^4, 4 1s in each column, n in each row
        n=16: A 2^14 x 2^16, 2^18 nnz, glpsol simplex 10 hours
"""
# keywords: linear programming, test case, generator, Latin-square
# https://stackoverflow.com/questions/57936789/many-vertex-test-problems-for-the-simplex-method
# https://math.stackexchange.com/questions/3370934/3d-permutation-matrices  -- 4d too

denis-bz

Stripy: percentile stripes for scatterplots

Keywords: scatterplot, percentiles, quantiles, visualize, regression, nonparametric

What does this show ? Consider a fat vertical line at a given x in one of these plots. The colored bands are, from low to high,

denis-bz

#!/usr/bin/env python3
""" triangles in a sparse graph """
# Keywords: sparse-graph, sparse-matrix, scipy, mesh, triangles
# w Polygon_mesh Mesh_generation ...

import numpy as np
from scipy import sparse
    # https://docs.scipy.org/doc/scipy/reference/sparse.csgraph.html

# some type names --

denis-bz

Invop() inverse operator for scipy.sparse eigenvalues with ARPACK

Problem: find a few eigenvalues λ and eigenvectors v of
A v = λ v, \ A a scipy.sparse matrix, largest or smallest |λ|
or K v = λ M v with stiffness matrix K and mass matrix M.

Purpose: experiment with different linear solvers, with verbose to track solver calls.
Keywords: scipy.sparse, linear-solvers, eigenvalue, generalized-eigenvalue, Arpack, logging

In the following examples, eigs( A [M] [Minv] [OPinv] [sigma] ... ) \