编辑代码

d=function(a,b){
    n1=length(a)
    n2=length(b)
    c=rep(0,n1+n2)
    for(i in 1:n1){
        for(j in 1:n2){
            c[i+j-1]=c[i+j-1]+a[i]*b[j]
        }
    }
    return(c)
}

dinv=function(t){
    n=length(t)
    z=rep(0,n)
    if(t[1]==0){
        return(z)
    }else{
        z[1]=t[1]
        for(i in 2:n){
            for(j in 1:(i-1)){
                z[i]=(z[i]+z[j]*t[i+1-j]/z[1])
            }
            z[i]=-z[i]
        }
        return(z)
    }
}

t=c(1,4,6,4,1)
z=dinv(t)
cat(z,"\n")
a=d(t,z)
cat(a)