Bisection method in R

Question

I am trying to solve an equation using Bisection method. However, when I try to run this, I get the below error

"Error in if ((fn(kVec, tVec, b) * fn(kVec, tVec, a) > 0) | (b > a)) { : 
  argument is of length zero"

Bisection method routine

bisect<-function(kVec,tVec,fn,b,a,tol=1e-15){
  i<-0
  r<-(b+a)/2
  res<-c(i,r,fn(kVec,tVec,r))
  if ((fn(kVec,tVec,b)*fn(kVec,tVec,a)>0)|(b>a)) {
    return('Improper start values') }
  else
    while (abs(fn(kVec,tVec,r))>tol) {
      i<-i+1
      if (fn(kVec,tVec,b)*fn(kVec,tVec,r)>0) {
        b<-r
        r<-(b+a)/2 
      }
      else {
        a<-r
        r<-(b+a)/2 
      }
      res<-rbind(res,c(i,r,fn(kVec, tVec,r)))  
  }
return(res)
}

Function to define the equation

FCfunc<-function(kVec,tVec,b){
for(i in 1:k){
    ((kVec[i]*(tVec[i]*exp(-tVec[i])-tVec[i-1]*exp(-b*tVec[i-1])))
    }
}

Calling bisection routine with some initial estimates

bisect(kVec,tVec,FCfunc,0.00001,10.00001,tol=10e-16) 

Answer 1

#bisection method
a<--give trial value-;a
b<--give trial value;b
f<-function(x){-give function-}
f(a)
f(b)
c<-(a+b)/2;c
while(f(c)!=0&&b-a>.00002)
{
    if(f(c)==0)
    {
        c
    }
    if(f(c)<0)
    {
        a<-c
    }
    else
    {
        b=c
    }
    {
        c<-(a+b)/2;c
    }
}
c