// ramp implements the ramp function
func (o *ElemP) ramp(x float64) float64 {
if o.Macaulay {
return fun.Ramp(x)
}
return fun.Sramp(x, o.βrmp)
}
func solve_problem(fnkey string, problem int) (opt *goga.Optimiser) {
// GA parameters
opt = new(goga.Optimiser)
opt.Default()
// options for report
opt.RptFmtF = "%.4f"
opt.RptFmtX = "%.3f"
opt.RptFmtFdev = "%.1e"
opt.RptWordF = "\\beta"
opt.HistFmt = "%.2f"
opt.HistNdig = 3
opt.HistDelFmin = 0.005
opt.HistDelFmax = 0.005
// FORM data
var lsft LSF_T
var vars rnd.Variables
// simple problem or FEM sim
if fnkey == "simple" {
opt.Read("ga-simple.json")
opt.ProbNum = problem
lsft, vars = get_simple_data(opt)
fnkey += io.Sf("-%d", opt.ProbNum)
io.Pf("\n----------------------------------- simple problem %d --------------------------------\n", opt.ProbNum)
} else {
opt.Read("ga-" + fnkey + ".json")
lsft, vars = get_femsim_data(opt, fnkey)
io.Pf("\n----------------------------------- femsim %s --------------------------------\n", fnkey)
}
// set limits
nx := len(vars)
opt.FltMin = make([]float64, nx)
opt.FltMax = make([]float64, nx)
for i, dat := range vars {
opt.FltMin[i] = dat.Min
opt.FltMax[i] = dat.Max
}
// log input
var buf bytes.Buffer
io.Ff(&buf, "%s", opt.LogParams())
io.WriteFileVD("/tmp/gosl", fnkey+".log", &buf)
// initialise distributions
err := vars.Init()
if err != nil {
chk.Panic("cannot initialise distributions:\n%v", err)
}
// plot distributions
if opt.PlotSet1 {
io.Pf(". . . . . . . . plot distributions . . . . . . . .\n")
np := 201
for i, dat := range vars {
plt.SetForEps(0.75, 250)
dat.PlotPdf(np, "'b-',lw=2,zorder=1000")
//plt.AxisXrange(dat.Min, dat.Max)
plt.SetXnticks(15)
plt.SaveD("/tmp/sims", io.Sf("distr-%s-%d.eps", fnkey, i))
}
return
}
// objective function
nf := 1
var ng, nh int
var fcn goga.MinProb_t
var obj goga.ObjFunc_t
switch opt.Strategy {
// argmin_x{ β(y(x)) | lsf(x) ≤ 0 }
// f ← sqrt(y dot y)
// g ← -lsf(x) ≥ 0
// h ← out-of-range in case Transform fails
case 0:
ng, nh = 1, 1
fcn = func(f, g, h, x []float64, ξ []int, cpu int) {
// original and normalised variables
h[0] = 0
y, invalid := vars.Transform(x)
if invalid {
h[0] = 1
return
}
// objective value
f[0] = math.Sqrt(la.VecDot(y, y)) // β
// inequality constraint
lsf, failed := lsft(x, cpu)
g[0] = -lsf
h[0] = failed
}
// argmin_x{ β(y(x)) | lsf(x) = 0 }
// f ← sqrt(y dot y)
// h0 ← lsf(x)
// h1 ← out-of-range in case Transform fails
case 1:
ng, nh = 0, 2
fcn = func(f, g, h, x []float64, ξ []int, cpu int) {
// original and normalised variables
h[0], h[1] = 0, 0
y, invalid := vars.Transform(x)
if invalid {
h[0], h[1] = 1, 1
return
}
// objective value
f[0] = math.Sqrt(la.VecDot(y, y)) // β
// equality constraint
lsf, failed := lsft(x, cpu)
h[0] = lsf
h[1] = failed
// induce minmisation of h0
//f[0] += math.Abs(lsf)
}
case 2:
opt.Nova = 1
opt.Noor = 2
obj = func(sol *goga.Solution, cpu int) {
// clear out-of-range values
sol.Oor[0] = 0 // invalid transformation or FEM failed
sol.Oor[1] = 0 // g(x) ≤ 0 was violated
// original and normalised variables
x := sol.Flt
y, invalid := vars.Transform(x)
if invalid {
sol.Oor[0] = goga.INF
sol.Oor[1] = goga.INF
return
}
// objective value
sol.Ova[0] = math.Sqrt(la.VecDot(y, y)) // β
// inequality constraint
lsf, failed := lsft(x, cpu)
sol.Oor[0] = failed
sol.Oor[1] = fun.Ramp(lsf)
}
default:
chk.Panic("strategy %d is not available", opt.Strategy)
}
// initialise optimiser
opt.Init(goga.GenTrialSolutions, obj, fcn, nf, ng, nh)
// solve
io.Pf(". . . . . . . . running . . . . . . . .\n")
opt.RunMany("", "")
goga.StatF(opt, 0, true)
io.Pfblue2("Tsys = %v\n", opt.SysTimeAve)
// check
goga.CheckFront0(opt, true)
// results
sols := goga.GetFeasible(opt.Solutions)
if len(sols) > 0 {
goga.SortByOva(sols, 0)
best := sols[0]
io.Pforan("x = %.6f\n", best.Flt)
io.Pforan("xref = %.6f\n", opt.RptXref)
io.Pforan("β = %v (%v)\n", best.Ova[0], opt.RptFref[0])
}
return
}
// RunFEM runs FE analysis.
func (o *FemData) RunFEM(Enabled []int, Areas []float64, draw int, debug bool) (mobility, failed, weight, umax, smax, errU, errS float64) {
// check for NaNs
defer func() {
if math.IsNaN(mobility) || math.IsNaN(failed) || math.IsNaN(weight) || math.IsNaN(umax) || math.IsNaN(smax) || math.IsNaN(errU) || math.IsNaN(errS) {
io.PfRed("enabled := %+#v\n", Enabled)
io.PfRed("areas := %+#v\n", Areas)
chk.Panic("NaN: mobility=%v failed=%v weight=%v umax=%v smax=%v errU=%v errS=%v\n", mobility, failed, weight, umax, smax, errU, errS)
}
}()
// set connectivity
if o.Opt.BinInt {
for cid, ena := range Enabled {
o.Dom.Msh.Cells[cid].Disabled = true
if ena == 1 {
o.Dom.Msh.Cells[cid].Disabled = false
}
}
} else {
for _, cell := range o.Dom.Msh.Cells {
cid := cell.Id
xid := o.Cid2xid[cid]
o.Dom.Msh.Cells[cid].Disabled = true
if Areas[xid] >= o.Opt.aEps {
o.Dom.Msh.Cells[cid].Disabled = false
}
}
}
// set stage
o.Analysis.SetStage(0)
// check for required vertices
nnod := len(o.Dom.Nodes)
for _, vid := range o.ReqVids {
if o.Dom.Vid2node[vid] == nil {
//io.Pforan("required vertex (%d) missing\n", vid)
mobility, failed, errU, errS = float64(1+2*nnod), 1, 1, 1
return
}
}
// compute mobility
if o.Opt.Mobility {
m := len(o.Dom.Elems)
d := len(o.Dom.EssenBcs.Bcs)
M := 2*nnod - m - d
if M > 0 {
//io.Pforan("full mobility: M=%v\n", M)
mobility, failed, errU, errS = float64(M), 1, 1, 1
return
}
}
// set elements' cross-sectional areas and compute weight
for _, elem := range o.Dom.Elems {
ele := elem.(*fem.ElastRod)
cid := ele.Cell.Id
xid := o.Cid2xid[cid]
ele.Mdl.A = Areas[xid]
ele.Recompute(false)
weight += ele.Mdl.Rho * ele.Mdl.A * ele.L
}
// run FE analysis
err := o.Analysis.SolveOneStage(0, true)
if err != nil {
//io.Pforan("analysis failed\n")
mobility, failed, errU, errS = 0, 1, 1, 1
return
}
// find maximum deflection
// Note that sometimes a mechanism can happen that makes the tip to move upwards
if o.VidU >= 0 {
eq := o.Dom.Vid2node[o.VidU].GetEq("uy")
uy := o.Dom.Sol.Y[eq]
umax = math.Abs(uy)
} else {
for _, nod := range o.Dom.Nodes {
eq := nod.GetEq("uy")
uy := o.Dom.Sol.Y[eq]
umax = utl.Max(umax, math.Abs(uy))
}
}
errU = fun.Ramp(umax - o.Opt.Uawd)
// find max stress
for _, elem := range o.Dom.Elems {
ele := elem.(*fem.ElastRod)
tag := ele.Cell.Tag
sig := ele.CalcSig(o.Dom.Sol)
smax = utl.Max(smax, math.Abs(sig))
errS = utl.Max(errS, o.Opt.CalcErrSig(tag, sig))
}
errS = fun.Ramp(errS)
// draw
if draw > 0 {
lwds := make(map[int]float64)
for _, elem := range o.Dom.Elems {
ele := elem.(*fem.ElastRod)
cid := ele.Cell.Id
lwds[cid] = 0.1 + ele.Mdl.A/20.0
}
o.Dom.Msh.Draw2d(true, false, lwds, 1)
//plt.Title(io.Sf("weight=%.3f deflection=%.6f", weight, umax), "")
//plt.SaveD("/tmp/goga", io.Sf("mesh-topology-%03d.eps", draw))
}
// debug
if false && (umax > 0 && errS < 1e-10) {
io.PfYel("enabled := %+#v\n", Enabled)
io.Pf("areas := %+#v\n", Areas)
io.Pf("weight = %v\n", weight)
io.Pf("umax = %v\n", umax)
io.Pf("smax = %v\n", smax)
io.Pf("errU = %v\n", errU)
io.Pf("errS = %v\n", errS)
// post-processing
msh := o.Dom.Msh
vid := msh.VertTag2verts[-4][0].Id
nod := o.Dom.Vid2node[vid]
eqy := nod.GetEq("uy")
uy := o.Dom.Sol.Y[eqy]
io.Pfblue2("%2d : uy = %g\n", vid, uy)
}
return
}
