# Getobjective does not return value of my objective function
**URL:** https://discourse.julialang.org/t/getobjective-does-not-return-value-of-my-objective-function/23061
**Category:** New to Julia
**Tags:** jump
**Created:** [April 12, 2019, 1:12am UTC](https://discourse.julialang.org/t/getobjective-does-not-return-value-of-my-objective-function/23061 "2019-04-12T01:12:16Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Y\_Li](https://discourse.julialang.org/u/Y_Li)
#### Post date: [April 12, 2019, 1:12am UTC](https://discourse.julialang.org/t/getobjective-does-not-return-value-of-my-objective-function/23061/1 "2019-04-12T01:12:16Z")
```julia
using MatpowerCases
using JuMP
using Ipopt
include("acopf_input.jl")
path = pwd()"/case.dat"
casefilename, refbus, loadscale, thermalLimitscale, extras, mvaBase = readconfig(path)
generators, generatorlist, buses, lines = readcase(casefilename, extras, loadscale, thermalLimitscale, mvaBase)
function solve_acopf(thermalLimitscale, generators, buses, lines)
numbuses = length(buses)
numlines = length(lines)
numgenerators = length(generators)
theta_u=deg2rad(float(extras["theta_u"]))
m=Model(solver=IpoptSolver())
PV = find(map(b->b.kind==:PV, buses))
PQ = find(map(b->b.kind==:PQ, buses))
REF = find(map(b->b.kind==:Ref, buses))
@assert length(REF) == 1
@variable(m,ir[1:numbuses]) #real current injected at node
@variable(m,ij[1:numbuses]) #immaginary current injected at node
@variable(m,irij[1:numlines]) #real current flow from i to j
@variable(m,ijij[1:numlines]) #immaginary current flow from i to j
@variable(m,irji[1:numlines])# real current flow from j to i
@variable(m,ijji[1:numlines])#reactive current flow from j to i
@variable(m,theta[1:numbuses])#bus angle
@variable(m,theta_ij[1:numlines])
@variable(m, gp[1:numgenerators])#Active power generated at certain generator
@variable(m, gq[1:numgenerators])#Reactive power generated
@variable(m, v[1:numbuses] >=0)#Bus voltage
@variable(m, vr[1:numbuses] >=0)#Bus voltage real part
@variable(m, vj[1:numbuses])#Bus voltage imanginary part
#Objective Functions
@NLobjective(m, Min, sum{gp[i]^2*generators[i].pi1 + gp[i]*generators[i].pi2+generators[i].pi3, i=numgenerators})
#AC transmission constraint
irij_constr=[]
ijij_constr=[]
irji_constr=[]
ijji_constr=[]
for i=1:numlines
@constraint(m, theta_ij[i]==(theta[lines[i].head]-theta[lines[i].tail]))
@constraint(m,-6.28 <=theta_ij[i]<=6.28 )
#current leaving i to j
@NLconstraint(m,irij[i] == lines[i].γ * v[lines[i].head] * cos(theta[lines[i].head])-v[lines[i].head] *sin(theta[lines[i].head])*lines[i].β-lines[i].γ * v[lines[i].tail] *cos(theta[lines[i].tail])+lines[i].β * v[lines[i].tail] *sin(theta[lines[i].tail]))
@NLconstraint(m,ijij[i] == (lines[i].β-lines[i].b_charge/2) * v[lines[i].head] * cos(theta[lines[i].head])+v[lines[i].head] *sin(theta[lines[i].head])*lines[i].γ-lines[i].β * v[lines[i].tail] *cos(theta[lines[i].tail])-lines[i].γ * v[lines[i].tail] *sin(theta[lines[i].tail]))
#Current leaving j towards i
@NLconstraint(m,irji[i] == lines[i].γ * v[lines[i].tail] * cos(theta[lines[i].tail])-v[lines[i].tail] *sin(theta[lines[i].tail])*lines[i].β-lines[i].γ * v[lines[i].head] *cos(theta[lines[i].head])+lines[i].β * v[lines[i].head] *sin(theta[lines[i].head]))
@NLconstraint(m,ijji[i] == (lines[i].β-lines[i].b_charge/2) * v[lines[i].tail] * cos(theta[lines[i].tail])+v[lines[i].tail] *sin(theta[lines[i].tail])*lines[i].γ-lines[i].β * v[lines[i].head] *cos(theta[lines[i].head])-lines[i].γ * v[lines[i].head] *sin(theta[lines[i].head]))
#Thermal Limits
if lines[i].Imax > 0
@constraint(m, -lines[i].Imax<=irij[i] <= lines[i].Imax)
@constraint(m, -lines[i].Imax<=ijij[i] <= lines[i].Imax)
@NLconstraint(m,irij[i]^2+ijij[i]^2<= lines[i].Imax^2)
@NLconstraint(m,irji[i]^2+ijji[i]^2<= lines[i].Imax^2)
end
end
#Nodal Current Balancing & bus voltage limit &nodal power balanceing
vr_constr=[]
vj_constr=[]
ir_constr=[]
ij_constr=[]
for i=1:numbuses
@constraint(m,-theta_u <=theta[i]<= theta_u)
@NLconstraint(m,vr[i]==v[i]*cos(theta[i]))
@NLconstraint(m,vj[i]==v[i]*sin(theta[i]))
@constraint(m,-buses[i].Vmax <= vr[i] <= buses[i].Vmax)
@constraint(m,-buses[i].Vmax <= vj[i] <= buses[i].Vmax)
@NLconstraint(m,(buses[i].Vmin)^2 <= vr[i]^2+vj[i]^2 <= (buses[i].Vmax)^2)#@1 to linearize
if buses[i].kind == :Ref
@constraint(m,theta[i] == 0)
elseif buses[i].kind == :PV #why this process
end
@NLconstraint(m, ir[i]==-sum{irij[k], k in buses[i].outlist}+sum{irij[k], k in buses[i].inlist}+vr[i]*buses[i].Gs-vr[i]*buses[i].Bs)
@NLconstraint(m, ij[i]==-sum{ijij[k], k in buses[i].outlist}+sum{ijij[k], k in buses[i].inlist}+vj[i]*buses[i].Gs-vj[i]*buses[i].Bs)
@NLconstraint(m, sum{gp[k], k in buses[i].genids}+vr[i]*ir[i]+vj[i]*ij[i]==buses[i].Pd)
@NLconstraint(m, sum{gq[k], k in buses[i].genids}+vj[i]*ir[i]-vr[i]*ij[i]==buses[i].Qd)
end
for i=1:numgenerators
@constraint(m, 0<=gp[i]<=generators[i].Pgmax)
@constraint(m, -generators[i].Qgmax<=gq[i]<=generators[i].Qgmax)
end
solve(m)
return getvalue(gp),getvalue(gq),getObjectiveValue(m),getvalue(vr),getvalue(vj), getvalue(irij),getvalue(ijij),getvalue(theta)
end
(gp_opt, gq_opt,obj,vr_opt,vj_opt, irij_opt,ijij_opt,theta_opt)=solve_acopf(thermalLimitscale, generators, buses, lines);
println(" ********************************************************************")
println("The optimal cost is ", obj, gp_opt,vr_opt,"Current flow is ",irij_opt)
println(" ********************************************************************")
```
So after I run the code the solver status is optimal and everything is fine. Compare the result with test case, they are also very similar. But the only problem is that getobjectivevalue() does not return the value of my objective function “sum{gp[i]^2\*generators[i].pi1 + gp[i]\*generators[i].pi2+generators[i].pi3, i=numgenerators}” rather, it returns the value of sum{gp[i], i=numgenerators}. May I ask what is the reason for this?
Thank you!
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [April 12, 2019, 2:34am UTC](https://discourse.julialang.org/t/getobjective-does-not-return-value-of-my-objective-function/23061/2 "2019-04-12T02:34:09Z")
Please read: [Please read: make it easier to help you](https://discourse.julialang.org/t/psa-make-it-easier-to-help-you/14757)
What is the error? `getObjectiveValue` should probably be `getobjectivevalue`.
---
### Author:  [@Y\_Li](https://discourse.julialang.org/u/Y_Li)
#### Post date: [April 12, 2019, 4:35pm UTC](https://discourse.julialang.org/t/getobjective-does-not-return-value-of-my-objective-function/23061/3 "2019-04-12T16:35:13Z")
Thank you for your reply! I change it to getobjectivevalue but the result returned is still not the value of my objective function.
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [April 12, 2019, 4:46pm UTC](https://discourse.julialang.org/t/getobjective-does-not-return-value-of-my-objective-function/23061/4 "2019-04-12T16:46:17Z")
There are two problems:
1.
```julia
@NLobjective(m, Min, sum{gp[i]^2*generators[i].pi1 + gp[i]*generators[i].pi2+generators[i].pi3, i=numgenerators})
```
doesn’t do what you think it does.
`i=numgenerators` will only add the last generator. You need `i=1:numgenerators`.
1.
It looks like you are using an old version of JuMP (indicated by `sum{}`). Update to the latest JuMP and use
```julia
@NLobjective(m, Min, sum(generators[i[.pi1 * gp[i]^2 + generators[i].pi2 * gp[i] + generators[i].pi3 for i in 1:numgenerators))
```
---
### Author:  [@Y\_Li](https://discourse.julialang.org/u/Y_Li)
#### Post date: [April 12, 2019, 4:49pm UTC](https://discourse.julialang.org/t/getobjective-does-not-return-value-of-my-objective-function/23061/5 "2019-04-12T16:49:32Z")
I change it to i=1:numgenerators and it returns my objective function value this time. Thank you so much for your time!