Description: book example autogenerated using nltransd.mod, nltrans.dat, and nltrans.run
Nonlinear transportation model
This is a variation of the linear transportation model presented on the Chapter 3 of the AMPL book, containing a nonlinear objective. There are a set of origin nodes, and a set of destination nodes (net model).
$$\sum \limits_{\substack{i \in ORIG \ j \in DEST}} rate[i,j] \cdot \frac{Trans[i,j]^{0.8}}{1 - \frac{Trans[i,j]}{limit[i,j]}}$$
The bigger the Trans[i,j]
value, the closer to limit[i,j]
(upper bound) so denominator tends to $1-1=0$ implying high costs.
Constraints:
$$\sum \limits_{j \in DEST} Trans[i,j] = supply[i]$$
$$\sum \limits_{i \in ORIG} Trans[i,j] = demand[j]$$
Remark: as the objective function is highly nonlinear, some bounds are fixed in order to help the solver and getting a consistent solution. The first guess for variables is away from zero in 0.5*limit[i,j]
.
Overwriting nltrans_final.mod
Ipopt 3.12.13: outlev=0
******************************************************************************
This program contains Ipopt, a library for large-scale nonlinear optimization.
Ipopt is released as open source code under the Eclipse Public License (EPL).
For more information visit http://projects.coin-or.org/Ipopt
******************************************************************************
Ipopt 3.12.13: Restoration Phase Failed.
suffix ipopt_zU_out OUT;
suffix ipopt_zL_out OUT;
Total_Cost = 354279
Trans [*,*] (tr)
: CLEV GARY PITT :=
DET 586.429 191.805 421.765
FRA 292.089 75.1764 532.735
FRE 365.333 370.173 364.494
LAF 488.914 0.0937081 510.992
LAN 298.74 0.000276411 301.26
STL 469.177 762.751 468.072
WIN 99.318 9.99922e-05 300.682
;