CODEWITHSUNDEEP
r
CringleVonChubbleslerry
CringleVonChubbleslerry

Reputation: 65

Evaluation of a polynomial using functions

I need some help creating a function that evaluates a polynomial of the form:

With the arguments of vector x and coefficient vector. I need to use a for loop to calculate to polynomial sum, but not to calculate the different values of x. The last thing I need to do is do an error check if the coefficient vector's length is less than 2. Here's what I have tried:

directpoly<-function(x,coef) {
  total=coef[1]
  for(n in length(coef)) {
    total<-total+coef[-1]*x^n-1
  }
  ifelse(length(coef)>2,"Vector is less than length 2")
}

I know that attempt is probably embarrassingly terrible but I'm very new to this program and very out of my depths, I've never coded in anything before. Thanks in advance.

Upvotes: 0

Views: 117

Answers (1)

St&#233;phane Laurent
St&#233;phane Laurent

Reputation: 84599

x <- 3
coefs <- c(4,5,3,1)
n <- length coefs 
result <- sum(coefs * x^(0:(n-1))

For the check: 

if(n < 2){
  stop("n must be > 1")
}

Upvotes: 2

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