Examples
 The following example represents truss with 9 joints and 16 members under forces applied to different joints.
 Input number of joints:
 Number of joints n>2: 9
 Input coordinates of joints:
 x1 : 0 y1 : 0 x2 ≥0 : 10 y2 ≥0 : 7.5 x3 ≥0 : 20 y3 ≥0 : 15 x4 ≥0 : 20 y4 ≥0 : 0 x5 ≥0 : 30 y5 ≥0 : 22.5 x6 ≥0 : 40 y6 ≥0 : 15 x7 ≥0 : 50 y7 ≥0 : 7.5 x8 ≥0 : 60 y8 ≥0 : 0 x9 ≥0 : 40 y9 ≥0 : 0

 Input truss members:
 First end (joint) of member # 1: 1 Second end (joint) of member # 1: 2 First end (joint) of member # 2: 1 Second end (joint) of member # 2: 4 First end (joint) of member # 3: 2 Second end (joint) of member # 3: 3 First end (joint) of member # 4: 2 Second end (joint) of member # 4: 4 First end (joint) of member # 5: 3 Second end (joint) of member # 5: 4 First end (joint) of member # 6: 3 Second end (joint) of member # 6: 5 First end (joint) of member # 7: 4 Second end (joint) of member # 7: 5 First end (joint) of member # 8: 4 Second end (joint) of member # 8: 9 First end (joint) of member # 9: 5 Second end (joint) of member # 9: 6 First end (joint) of member # 10: 5 Second end (joint) of member # 10: 9 First end (joint) of member # 11: 6 Second end (joint) of member # 11: 7 First end (joint) of member # 12: 6 Second end (joint) of member # 12: 9 First end (joint) of member # 13: 7 Second end (joint) of member # 13: 8 First end (joint) of member # 14: 7 Second end (joint) of member # 14: 9 First end (joint) of member # 15: 8 Second end (joint) of member # 15: 9

 Input constraints:
 Number of joint of horizontal constraint # 1: 1 Number of joint of vertical constraint # 1: 1 Number of joint of horizontal constraint # 2: Number of joint of vertical constraint # 2: 8

 Input vertical and horizontal components of external forces applied to joints:
 X1 : Reaction Y1 : Reaction X2 : Y2 : -6 X3 : Y3 : -6 X4 : -4 Y4 : X5 : Y5 : -6 X6 : Y6 : -11 X7 : Y7 : -8 X8 : Y8 : Reaction X9 : Y9 :

 Output:

The horizontal reaction is: H1=4 .  The vertical reactions are: V1=17, V8=20 .

The computed internal forces are: N12=-28.333; N14=18.667; N23=-23.333; N24=-5; N34=-6; N35=-23.333; N45=9.849; N49=14.667; N56=-26.667; N59=16.415; N67=-26.667; N69=-11; N78=-33.333; N79=-6.667; N89=26.667;

 Solution
Reactions:
Equilibrium equation of truss with respect to x-axis:
H1=-X4=+4=4;

Equilibrium equation of truss (the sum of moments about joint with number 8):
V1=(+Y2(x2-x8)+Y3(x3-x8)+Y5(x5-x8)+Y6(x6-x8)+Y7(x7-x8)-X4(y4-y8)-H1(y1-y8))/(x8-x1)=(-6(10-60)-6(20-60)-6(30-60)-11(40-60)-8(50-60)+4(0-0)-4(0-0))/(60-0)=17;

Equilibrium equation of truss with respect to y-axis:
V8=-Y2-Y3-Y5-Y6-Y7-V1=+6+6+6+11+8-17=20;

Internal forces of the truss:
Equilibrium equations of joint with number 1 with respect to y and x axes:
N12v12+N14v14+V1=0;
N12h12+N14h14+H1=0;
After substitution of known values we have the system of linear equations
0.6N12+-0N14+17=0;
0.8N12+1N14+4=0;
The solution of the system: N12=-28.333; N14=18.667
Equilibrium equations of joint with number 2 with respect to y and x axes:
N23v23+N24v24+N21v21+Y2=0;
N23h23+N24h24+N21h21=0;
After substitution of known values we have the system of linear equations
0.6N23-0.6N24+11=0;
0.8N23+0.8N24+22.667=0;
The solution of the system: N23=-23.333; N24=-5
Equilibrium equations of joint with number 3 with respect to y and x axes:
N34v34+N35v35+N32v32+Y3=0;
N34h34+N35h35+N32h32=0;
After substitution of known values we have the system of linear equations
-1N34+0.6N35+8=0;
-0N34+0.8N35+18.667=0;
The solution of the system: N34=-6; N35=-23.333
Equilibrium equations of joint with number 4 with respect to y and x axes:
N45v45+N49v49+N41v41+N42v42+N43v43=0;
N45h45+N49h49+N41h41+N42h42+N43h43+X4=0;
After substitution of known values we have the system of linear equations
0.914N45+-0N49-9=0;
0.406N45+1N49-18.667=0;
The solution of the system: N45=9.849; N49=14.667
Equilibrium equations of joint with number 5 with respect to y and x axes:
N56v56+N59v59+N53v53+N54v54+Y5=0;
N56h56+N59h59+N53h53+N54h54=0;
After substitution of known values we have the system of linear equations
-0.6N56-0.914N59-1=0;
0.8N56+0.406N59+14.667=0;
The solution of the system: N56=-26.667; N59=16.415
Equilibrium equations of joint with number 6 with respect to y and x axes:
N67v67+N69v69+N65v65+Y6=0;
N67h67+N69h69+N65h65=0;
After substitution of known values we have the system of linear equations
-0.6N67-1N69-27=0;
0.8N67+-0N69+21.333=0;
The solution of the system: N67=-26.667; N69=-11
Equilibrium equations of joint with number 7 with respect to y and x axes:
N78v78+N79v79+N76v76+Y7=0;
N78h78+N79h79+N76h76=0;
After substitution of known values we have the system of linear equations
-0.6N78-0.6N79-24=0;
0.8N78-0.8N79+21.333=0;
The solution of the system: N78=-33.333; N79=-6.667
Equilibrium state of joint with number 8:
N89h89+N87h87=0;
After substitution of known values we have
-1N89+26.667=0;
The solution is N89=26.667;

Here hij and vij are cosine and sine of the angle between x-axis and truss member connecting joints i and j .
They are calculated using formulas: hij=(xj-xi)/lij;   vij=(yj-yi)/lij ,
lij is the distance between joints i and j (the length of truss member).
For the considered truss: l12=12.5; l14=20; l23=12.5; l24=12.5; l34=15; l35=12.5; l45=24.622; l49=20; l56=12.5; l59=24.622; l67=12.5; l69=15; l78=12.5; l79=12.5; l89=20;
h12=0.8; h14=1; h23=0.8; h24=0.8; h34=-0; h35=0.8; h45=0.406; h49=1; h56=0.8; h59=0.406; h67=0.8; h69=-0; h78=0.8; h79=-0.8; h89=-1;
v12=0.6; v14=-0; v23=0.6; v24=-0.6; v34=-1; v35=0.6; v45=0.914; v49=-0; v56=-0.6; v59=-0.914; v67=-0.6; v69=-1; v78=-0.6; v79=-0.6; v89=-0;