Singular Manual: finitediff_lib

> | ### D.15.6 finitediff_lib Issues: installation of qepcadfilter.pl needs to be solved tests for (nearly) all procedures are missing global variables needs to be cleaned temporary files needs to be cleaned temporary file names need to be unique (think about multiple instances) pollution of global Top namespace must be solved u is not a good name for a procedure Library: finitediff.lib Purpose: procedures to compute finite difference schemes for linear differential equations Author: Christian Dingler Overview: Using `qepcad`/`qepcadsystem` from this library requires the program `qepcad` to be installed. You can download `qepcad` from http://www.usna.edu/CS/qepcadweb/B/QEPCAD.html Procedures:
> D.15.6.1 visualize |  | shows a scheme in index-notation
> D.15.6.2 u |  | gives some vector; depends on @derivatives
> D.15.6.3 scheme |  | computes the finite difference scheme defined by v1,..,vn
> D.15.6.4 laxfrT |  | Lax-Friedrich-approximation for the time-direction
> D.15.6.5 laxfrX |  | Lax-Friedrich-approximation for the space-direction
> D.15.6.6 forward |  | forward-approximation
> D.15.6.7 backward |  | backward-approximation
> D.15.6.8 central1st |  | central-approximation of first order
> D.15.6.9 central2nd |  | central-approximation of second order
> D.15.6.10 trapezoid |  | trapezoid-approximation
> D.15.6.11 midpoint |  | midpoint-approximation
> D.15.6.12 pyramid |  | pyramid-approximation
> D.15.6.13 setinitials |  | constructs and sets the basering for further computations
> D.15.6.14 errormap |  | performs the Fouriertransformation of a poly
> D.15.6.15 matrixsystem |  | gives the scheme of a pde-system as one matrix
> D.15.6.16 timestep |  | gives the several timelevels of a scheme derived from a pde-system
> D.15.6.17 fouriersystem |  | performs the Fouriertransformation of a matrix scheme
> D.15.6.18 PartitionVar |  | partitions a poly into the var(n)-part and the rest
> D.15.6.19 ComplexValue |  | computes the complex value of f, var(1) being the imaginary unit
> D.15.6.20 VarToPar |  | substitute var(i) by par(i)
> D.15.6.21 ParToVar |  | substitute par(i) by var(i)
> D.15.6.22 qepcad |  | ask QEPCAD for equivalent constraints to f<1
> D.15.6.23 qepcadsystem |  | ask QEPCAD for equivalent constraints to all eigenvals of some matrices being <1

User manual for Singular version 4.4.1, 2025, generated by texi2html.