# R program to illustrate
# call function
  
# Calling call() function
x <- call("sin", 23)
y <- call("cos", 0)
x
y
  
# Evaluating values of call
eval(x)
eval(y)

sin(23)
cos(0)
[1] -0.8462204
[1] 1

# R program to illustrate
# call function
  
# Calling call() function
x <- call("round", 10.5)
x 
  
# Initializing a round character
f <- "round"
  
# Calling call() function
call(f, quote(A)) 

round(10.5)
round(A)

# R program to illustrate
# call function
  
# Initializing round value
# without its character
f <- round
  
# Calling call() function
# which will give an error
# bcs the argument should be
# a character string
call(f, quote(A))

Error in call(f, quote(A)) : first argument must be a character string
Execution halted