General SG programs:

diffsg:

This is a function to calculate derivatives of the map f: R^m1 -> R^m2 defined by restricting an (m1)st level complex of delta circuits to an (m2)nd level one. We approximate derivatives with respect to perturbing each edge, and for each edge in the restriction, using difference quotients with a variety of sizes of perturbation

eip.m

Computes the energy inner product of two functions on SG

emeasure

Computes energy measure for a given harmonic function and cell

energy

Computes energy of a function

f0

A contractive similarity of the plane centered at 0 of dilation factor 1/2

fi

A contractive similarity of the plane centered at the point qi of dilation factor 1/2

findps

Returns relative coordinates to use when printing out a table of values at vertex points on SG

gaskplot

Plots a function defined on the level m vertices of SG, with edges connecting adjacent vertices

harm

Computes the harmonic extension from V_0 to V_1 of a harmonic function.

harmonic

Computes the harmonic extension (given boundary points) to a particular level

kusuoka:

Calculates the Kusuoka measure of a cell

plotemeasure

Plots the values of an energy measure

plotkusuoka

Plots the Kusuoka measure

radon

Calculates the Radon-Nikodym derivative of an energy measure with respect to the Kusuoka measure

qcontract

Applies the function fi to a column of coordinate pairs

SGdata

A reference file with some important matrices for SG

SGedges

Computes the coordinates of the midpoints of all level m edges of SG

sgyprint

Prints the values of a function on the vertices of SG

Wordm

Performs a sequence of contractions on a set of vectors (in a matrix) in $R^{2}$ given a word w

Wordv

Performs a sequence of contractions on a vector given a word w



Indexing:

wordmatrix

Gives a matrix of all words of length m consisting of 0,1,2

address

Returns a vector listing the address of a given index k in a level m SG-type ordering (TLR ordering)

alternateaddress

Finds the alternative address for a given point in an SG ordering

alternateindex

Finds the alternative index for a given point in TLR ordering on SG.

indexsg

Finds the index in TLR ordering corresponding to a given address

gneighbors

This function finds the addresses of those edges which are incident to a given vertex

mindices.m

A headache-saving formula for the jth group of 3^m consecutive indices

mixup

Accepts a vector $y$ of size 3^m1, for some m1, and a permutation $indices$ of size 3^m2, for m2 <= m1, and scrambles the 3^m2 subvectors of y (each of size 3^(m1-m2)) according to the permutation

permutecells

Composes a function f:SG->R with a permutation of the cells of SG

reorder

Just a simple function to reorder a vector from largest to smallest element

singleindices

Solves the problem of performing calculations such as computing the spectrum of the Laplacian on SG when our chosen data storage scheme is redundant

vneighbors

Finds the addresses of those edges which are incident to a given vertex



Graph restrictions and their relation to the Kusuoka measure:

dergraph

Plots derivatives of resistances of restriction of graph after perturbing an edge

derword

Computes derivative measures

doword

Computes measures on all cells of a level m graph

ds

Compute the derivatives of the resistances of the restricted graph with respect to perturbing each edge individually by a small t (see inside comments on how we use 3^m by 3 matrices in describing Y-networks

dy

Performs Delta-Y transformation on resistances of a Delta graph.

net

Produces coordinates of edges of Y-network of level m.

ninetothree

A level 1 Y-network of resistors to a single Y-circuit

omatrix

Gives a matrix with zeros everywhere except at one specified entry

plotder

Plots derivatives of resistances of Y graph after perturbing edges of an m-cell of the level m Y-network.

plotpert

Plots derivatives when only perturbing an edge.

radonder

Calculates radon-nikodym derivative of the derivative measures with respect to the Kusuoka measure.

rcol

Produces a concatenation of each step of the restriction of a system of resistors on SG (in Y-circuits)

restrict

This function computes the restriction of an (m1)st level network of resistors to an (m2)nd level such network, where a network at the mth level is the stacking of three (m-1)st level networks, and a 1st level network is a Y shaped network.

restrictall

Computes the restriction of a level m Y-network of resistors on SG to a single Y-circuit on the boundary points of SG.

restrictseq

Stores the intermediate computations involved in restricting a function between two levels of a Y-circuit. (Note: The point of this is that if you want to perform a restriction of a function that is perturbed on only one cell, you can save computation by simply executing this function ahead of time and, instead of doing redundant calculations, simply reading the restriction data for all cells not containing the perturbed cell since those remain unchanged).

smartrestrict

This is a computation-saving program for calculating restrictions of Y-networks of resistors. Performs the restriction of an m1-level SG-circuit to an m2-level circuit.

ydelta

Finds the delta-circuit of resistors on three vertices which is equivalent to an inputed y-circuit on the same three vertices with a central fourth vertex added.



Laplacians on the Sierpinski Gasket

claplacian

Calculates the Laplacian of 1 (the constant function).

defnstep:

Defines a step function on a level m graph approximation of SG.

deltarestrict

Restricts a Delta network of resistors

deltay

Computes a Y network equivalent to a (single) given Delta network of resistors.

diffquot

Computes a difference quotient approximation to a directional derivative of the map f: R^{m1} -> R^{m2} which takes a level m1 Delta network of resistors and restricts to a level m2 network.

diffquotSeq

This is a computation-saving version of diffquot.m (runs much faster for m1 >= 7 or so).

doetaplot

Makes a plot of the Weyl ratio for a computed spectrum, which is assumed to be stored as the variable “cspec”.

doplot

Once you have computed the spectrum of a conformal Laplacian, doplot allows you to create a plot of the Weyl file.

doSGweylratioplots

Script to print out pictures of several Weyl ratio plots.

dospectrum

Script to calculate the spectrum for the Dirichlet Laplacian, assuming a conformal factor g and level m are given.

dostepfunc

This is what I used to make conformal factors to put on SG. I tried to come up with some wavy sinusoidal thing that wouldn’t have any symmetry.

dsplaplacian

Returns the Dirichlet spectrum of the Laplacian for the conformal factor g using level m approximation.

edgefunc

Allows one to define an edge function on SG by inputting a function on R^2, and calculating the value of the function at the midpoint of each edge, where we use embedding of SG into R^2 such that the vertices form equilateral triangles.

edgeplot

Creates a graphic plot of a level m edge function on SG.

flaplacian

This function takes an inline function of the plane and computes its values at level m vertex points on a certain embedding of SG in the plane (as in an equilateral triangle with boundary points (0,0), (1/2,sqrt(3)/2),and (sqrt(3)/2,1/2)), then takes the level m laplacian of the resulting function and produces a plot of it.

formatcurrentSGweylratioplot

Labels the current Weyl ratio plot with ‘log(x)’ on the x-axis and ‘N(x)/x^\beta’ on the y-axis.

formattedratio

Changes a decimal number into a standard format to append to a file name.

funcdefn

This function allows the inputing of an R^2 function whose value to find on the junction points of a certain embedding of SG into the plane.

laplacian

This function accepts a function $u$ stored as a vector of length $3^(m+1)$ and a conformal factor $g$ of the same length, and computes the g-laplacian of u.

makeSGweylratioplot

Script to make a plot of the Weyl ratio for a conformal Laplacian once the spectrum has been computed

mlaplacian

Calculates the matrix corresponding to the Weyl ratio

nsplaplacian

This function computes the Neumann spectrum of the conformal laplacian with factor g size of g = 3^(m+1)

printcurrentSGweylratioplot

Script to print the current Weyl ratio plot under a coherent naming scheme

ptlaplacian

Calculates the laplacian of a function at a single point

spectralgaps

Calculates the gaps between subsequent eigenvalues of the Laplacian.



Miscellaneous:

clover

Plots Vicek graphs

log3

computes log base 3.

pdim

computes p dimension of an energy measure.

plot3c

does color point plot (Matlab only does color plot in the meshplot, as far as I know).

reorder

reorders a vector of values.

tenergy

computes energy of functions on the tetrahedral Sierpinski Gasket.

tetraSG

plots tetrahedral Sierpinski Gasket.

loopprint

allows printing of a table of values into an SG-type arrangement.

pdim

computes  L_p dimensions.