Integral of scilab polynomials

How do you find out the integral of an expression of polynomials in scilab ?

I have this code:

clc;
clear;

x=poly(0,"x");
printf("Digite a expressão para calcular:");
 mfun=input("");
printf("MENU DE OPÇÕES\n");
printf("1-DERIVADA\n");
printf("2-INTEGRAL\n");
printf("3-MAX E MIN RELATIVOS\n");
printf("4-EXTREMOS\n");
printf("5-DOMINIO\n");
printf("6-IMAGEM\n");
printf("0-SAIR\n");
opcao=input("Digite um numero:");

    if(opcao==0) then
        printf("\nVocê optou por sair do programa!");
end
while(opcao<>0 )


select opcao




case 1 then
    if(i==0) then
       z=derivat(mfun);
       i=i+1;
   end
     if(i<>0)then 
         z=derivat(z);
         end
       disp(z);

    case 2 then
        printf("INTEGRAL");

    case 3 then
    printf("MAX MIN");

    case 4 then
    printf("EXTREMOS");


    case 5 then
        printf("DOMINIO");

    case 6 then
        printf("A imagem de sua função é: %d",opcao);





end
    printf("\n MENU DE OPÇÕES\n");
    printf("1-DERIVADA\n");
    printf("2-INTEGRAL\n");
    printf("3-MAX E MIN RELATIVOS\n");
    printf("4-EXTREMOS\n");
    printf("5-DOMINIO\n");
    printf("6-IMAGEM\n");
    printf("0-SAIR\n");
    opcao=input("Digite um numero:");
    if(opcao==0) then
        printf("\nVocê optou por sair do programa!");
end
end

So far I've been able to make the polynomial derivative work, I can extract the derivative of the typed expression. I would like to know if there is any way to do the same with integral. Can someone help me?

I have already rolled out the entire documentation practically and found some integral commands like intg, etc. But these do not give integral to polynomials (you have to by the value of the variables). If somebody has some suggestion of function or maybe some command that maybe can help me, I thank you!

Expected input:

f(x)=2x²+4x

Expected Exit:

x³ + 2x²