> cd graphs

> ls

Demmel			clusters.mat		misluby.m
G3_circuit.mat		coAuthorsDBLP.mat	misseq.m
PGPgiantcompo.mat	dhist.m			plotccd.m
bcsstk08.mat		eigsvdgui.m		plotdegs.m
bfslevels.m		gploth.m		plotdegs.m~
btermatch.m		graphs.mat		rmat.m
ccoeff.m		matstats.m		rmat.m~
circuit_3.mat		meshes.mat		rmatstats.m
clustereg.m		meshpart		samplegraphs.mat

> load meshes
> whos
  Name              Size               Bytes  Class     Attributes

  Airfoil        4253x4253            495328  double    sparse    
  Amap           4253x1                34024  double              
  Axy            4253x2                68048  double              
  Eppstein        547x547              63248  double    sparse    
  Exy             547x2                 8752  double              
  Rmat           1024x1024            349096  double    sparse    
  Rmat64           64x64                9096  double    sparse    
  Rxy            1024x2                16384  double              
  Rxy64            64x2                 1024  double              
  Smallmesh       136x136              14600  double    sparse    
  Sxy             136x2                 2176  double              
  Tapir          1024x1024            115656  double    sparse    
  Txy            1024x2                16384  double              
  ans               1x49                  98  char                

> A = Airfoil;
> gplotg(A,Axy),shg
> figure,spy(A),shg
> Axy

Axy =
   1.0e+09 *
         0    1.2378
    0.0007    1.4748
    ...
    4.2343    0.9827
    4.2950    3.2226

>size(Axy)
ans =
        4253           2
> size(A)
ans =
        4253        4253

> A
A =
   (1,1)        6
   (2,1)       -1
   ...
(4251,4253)    -1
(4253,4253)     6

> clc

> A = randn(6)
A =
    0.5377   -0.4336    0.7254    1.4090    0.4889    0.8884
    1.8339    0.3426   -0.0631    1.4172    1.0347   -1.1471
   -2.2588    3.5784    0.7147    0.6715    0.7269   -1.0689
    0.8622    2.7694   -0.2050   -1.2075   -0.3034   -0.8095
    0.3188   -1.3499   -0.1241    0.7172    0.2939   -2.9443
   -1.3077    3.0349    1.4897    1.6302   -0.7873    1.4384

> b = randn(6,1)
b =
    0.3252
   -0.7549
    1.3703
   -1.7115
   -0.1022
   -0.2414

> x = A \ b
x =
   -0.7453
   -0.2627
    0.1880
   -0.0871
    0.9664
    0.1418

> A*x-b
ans =
   1.0e-15 *
   -0.1110
   -0.7772
    0.2220
    0.2220
   -0.0833
    0.1665

> lugui(A)

> [L,U,P] = lu(A)
L =
    1.0000         0         0         0         0         0
   -0.3817    1.0000         0         0         0         0
    0.5789    0.2330    1.0000         0         0         0
   -0.8119    0.7854    0.4376    1.0000         0         0
   -0.2380    0.1011    0.8383    0.2120    1.0000         0
   -0.1411   -0.2043   -0.0089    0.3048   -0.2321    1.0000
U =
   -2.2588    3.5784    0.7147    0.6715    0.7269   -1.0689
         0    4.1353    0.0678   -0.9512   -0.0260   -1.2175
         0         0    1.0601    1.4631   -1.2020    2.3408
         0         0         0    2.0691    2.1713   -2.0831
         0         0         0         0    1.2119   -0.7636
         0         0         0         0         0   -2.8654
P =
     0     0     1     0     0     0
     0     0     0     1     0     0
     0     0     0     0     0     1
     0     1     0     0     0     0
     1     0     0     0     0     0
     0     0     0     0     1     0

> A = randn(1000);
> b = randn(1000,1);

> x = A\b;