Method add

ecgo/builder/api.go:55–93

returns res = Σ(vars) or res = vars[0] - Σ(vars[1:]) if sub == true.

(vars []int, sub bool)

// returns res = Σ(vars) or res = vars[0] - Σ(vars[1:]) if sub == true.
func (builder *builder) add(vars []int, sub bool) frontend.Variable {
	// check if all variables are constants
	allConst := true
	if sum, ok := builder.constantValue(vars[0]); ok {
		for _, x := range vars[1:] {
			if v, ok := builder.constantValue(x); ok {
				if sub {
					sum = builder.field.Sub(sum, v)
				} else {
					sum = builder.field.Add(sum, v)
				}
			} else {
				allConst = false
				break
			}
		}
		if allConst {
			return builder.toVariable(sum)
		}
	}

	coef := make([]constraint.Element, len(vars))
	coef[0] = builder.tOne
	if sub {
		for i := 1; i < len(vars); i++ {
			coef[i] = builder.field.Neg(builder.tOne)
		}
	} else {
		for i := 1; i < len(vars); i++ {
			coef[i] = builder.tOne
		}
	}
	builder.instructions = append(builder.instructions, irsource.Instruction{
		Type:        irsource.LinComb,
		Inputs:      vars,
		LinCombCoef: coef,
	})
	return builder.addVar()
}

// Neg returns the negation of the given variable.
func (builder *builder) Neg(i frontend.Variable) frontend.Variable {