func exprGrow(e ExprType, egfunc ExprGenFunc, egp *prob.TreeParams, rng *rand.Rand) Expr { if e == -1 { return egfunc(egp, rng) } switch { case e == TIME: return NewTime() case e == VAR: p := egp.UsableVars[rng.Intn(len(egp.UsableVars))] return NewVar(p) case e == CONSTANT: i := egp.CoeffCount egp.CoeffCount++ return NewConstant(i) case e == CONSTANTF: return NewConstantF(rng.NormFloat64() * 2.0) case e == SYSTEM: return NewSystem(rng.Intn(egp.NumSys)) case e == NEG: egp.CurrDepth++ return NewNeg(egfunc(egp, rng)) case e == ABS: egp.CurrDepth++ return NewAbs(egfunc(egp, rng)) case e == SQRT: egp.CurrDepth++ return NewSqrt(egfunc(egp, rng)) case e == SIN: egp.CurrDepth++ egp.InTrig = true tmp := NewSin(egfunc(egp, rng)) egp.InTrig = false return tmp case e == COS: egp.CurrDepth++ egp.InTrig = true tmp := NewCos(egfunc(egp, rng)) egp.InTrig = false return tmp case e == TAN: egp.CurrDepth++ egp.InTrig = true tmp := NewTan(egfunc(egp, rng)) egp.InTrig = false return tmp case e == EXP: egp.CurrDepth++ return NewExp(egfunc(egp, rng)) case e == LOG: egp.CurrDepth++ return NewLog(egfunc(egp, rng)) case e == POWI: egp.CurrDepth++ return NewPowI(egfunc(egp, rng), (rng.Int()%7)-3) case e == POWF: egp.CurrDepth++ return NewPowF(egfunc(egp, rng), rng.Float64()*3.0) case e == POWE: egp.CurrDepth++ return NewPowE(egfunc(egp, rng), egfunc(egp, rng)) case e == ADD: egp.CurrDepth++ add := NewAdd() add.Insert(egfunc(egp, rng)) add.Insert(egfunc(egp, rng)) return add case e == MUL: egp.CurrDepth++ mul := NewMul() mul.Insert(egfunc(egp, rng)) mul.Insert(egfunc(egp, rng)) return mul case e == DIV: egp.CurrDepth++ return NewDiv(egfunc(egp, rng), egfunc(egp, rng)) } return NewNull() }