fem_check21a_tri.c running 
Given 3 ux + 2 uy + u = 2 x + 3 y + 13 
Analytic solution u(x,y) =  1 + 2 x + 3 y 
triquad ready for integration over triangles
about to read triangles from 22_t.tri
 1  2  0
index=1, last=2
index=4, last=5
index=7, last=8
tri 0 has vertices 1  2  0
 1  0  3
index=1, last=2
index=4, last=5
index=7, last=8
tri 1 has vertices 1  0  3
 2  3  0
index=1, last=2
index=4, last=5
index=7, last=8
tri 2 has vertices 2  3  0

3 triangles read from 22_t.tri
subtracting minvert=0 from all vertices, using base zero
finding unique of nold=9
found unique of n=4
about to read boundary from 22_t.bound
 1  2
index=1, last=2
index=4, last=5
boundary segment nbound=0 has vertices 1, 2
 2  3
index=1, last=2
index=4, last=5
boundary segment nbound=1 has vertices 2, 3
 3  1
index=1, last=2
index=4, last=5
boundary segment nbound=2 has vertices 3, 1

read Dirichlet boundaries from 22_t.bound
subtracting minvert=0 from all vertices, using base zero
finding unique of nold=6
found unique of n=3
freevert na=4, nb=3
freevert nc free = 1
unique boundary 1
unique boundary 2
unique boundary 3
number of free vertices is 1
free vertex 0
about to read coordinates from 22_t.coord
  0.0  0.0
index=2, last=5
index=7, last=10
coordinate 0 at  0.0, 0.0
 -0.1 -0.1
index=1, last=5
index=6, last=10
coordinate 1 at  -0.1, -0.1
  0.0  0.1
index=2, last=5
index=7, last=10
coordinate 2 at  0.0, 0.1
  0.1 -0.1
index=2, last=5
index=6, last=10
coordinate 3 at  0.1, -0.1
coordinates read from 22_t.coord
xmin=-0.1, xmax=0.1, ymin=-0.1, ymax=0.1
nvert=4, nbound=3, nuniqueb=3, nfree=1, ntri=3
compute global stiffness matrix 
computing local stiffness matrix for triangle 0
nodes i1=1, i2=2, i3=0
coord (-0.1,-0.1) (0.0,0.1) (0.0,0.0) 
cm matrix  of  am cm = ym   solve for cm 
 0.0 -10.0 -0.0
cm matrix  of  am cm = ym   solve for cm 
 0.0 -10.0 10.0
cm matrix  of  am cm = ym   solve for cm 
 1.0 20.0 -10.0
tri_int1a running with np=3, nv=9
integral=0.06749999999999987, at i=0, j=0
intg fg =0.021583333333333288, at i=0
integral=-0.04958333333333323, at i=1, j=0
integral=-0.016249999999999966, at i=2, j=0
finished k=0
computing local stiffness matrix for triangle 1
nodes i1=1, i2=0, i3=3
coord (-0.1,-0.1) (0.0,0.0) (0.1,-0.1) 
cm matrix  of  am cm = ym   solve for cm 
 0.0 -5.0 -5.0
cm matrix  of  am cm = ym   solve for cm 
 1.0 0.0 10.0
cm matrix  of  am cm = ym   solve for cm 
 0.0 5.0 -5.0
tri_int1a running with np=3, nv=9
integral=0.06833333333333322, at i=0, j=0
intg fg =0.042833333333333265, at i=0
integral=-0.08249999999999985, at i=1, j=0
integral=0.01749999999999997, at i=3, j=0
finished k=1
computing local stiffness matrix for triangle 2
nodes i1=2, i2=3, i3=0
coord (0.0,0.1) (0.1,-0.1) (0.0,0.0) 
cm matrix  of  am cm = ym   solve for cm 
 0.0 10.0 10.0
cm matrix  of  am cm = ym   solve for cm 
 0.0 10.0 0.0
cm matrix  of  am cm = ym   solve for cm 
 1.0 -20.0 -10.0
tri_int1a running with np=3, nv=9
integral=-0.13249999999999973, at i=0, j=0
intg fg =0.021749999999999957, at i=0
integral=0.08374999999999982, at i=2, j=0
integral=0.05041666666666656, at i=3, j=0
finished k=2
tri 0 has vertices 1, 2, 0
tri 1 has vertices 1, 0, 3
tri 2 has vertices 2, 3, 0
vertices, coordinates and analytic values 
coordinate 0 at 0.0, 0.0, uana=1.0
coordinate 1 at -0.1, -0.1, uana=0.5
coordinate 2 at 0.0, 0.1, uana=1.3
coordinate 3 at 0.1, -0.1, uana=0.8999999999999999
k computed stiffness matrix, if debug 
K(0,0)=0.003333333333333355
K(0,1)=-0.13208333333333308
K(0,2)=0.06749999999999987
K(0,3)=0.06791666666666653
K(1,0)=0.0
K(1,1)=1.0
K(1,2)=0.0
K(1,3)=0.0
K(2,0)=0.0
K(2,1)=0.0
K(2,2)=1.0
K(2,3)=0.0
K(3,0)=0.0
K(3,1)=0.0
K(3,2)=0.0
K(3,3)=1.0
f computed forcing function and boundary, if debug 
F(0)=0.0861666666666665, ug[0]=0.0
F(1)=0.5, ug[1]=0.0
F(2)=1.3, ug[2]=0.0
F(3)=0.8999999999999999, ug[3]=0.0
ug computed Galerkin, Ua analytic, error 
ug[0]=0.9999999999999964, Ua=1.0, err=-3.552713678800501E-15
ug[1]=0.5, Ua=0.5, err=0.0
ug[2]=1.3, Ua=1.3, err=0.0
ug[3]=0.8999999999999999, Ua=0.8999999999999999, err=0.0
                 maxerr=3.552713678800501E-15, avgerr=8.881784197001252E-16