$HistoryLength=0;
SetDirectory["/home/campus03/struther/Desktop/Link to Courses/5580/Matrices"]
Data=Import["Gmat.m","TABLE"];
n=Length[Data];
G = SparseArray[
Table[
{i,j,a}=Data[[k]];
{i,j}->a,
{k, n}]
]

Histogram[ 
Data=Table[Length[ArrayRules[G[[i]]]]-1,
{i, Length[G]}]]

Tally[Data]

x=RandomReal[{-1,1},{Length[G]}];
NIter=10;
Timing[Do[y=G.x,{NIter}];][[1]]/NIter

evalsBig=Eigenvalues[G,10]

evalsSmall=Eigenvalues[G,-10]

ListLogPlot[evalsBig,
PlotRange->All]

b=Cos[Sort[RandomReal[{0,π},Length[G]]]];
Timing[x=LinearSolve[G,b];]
Norm[G.x-b]

MatrixPlot[G]