R Bridge Week 1 Assignment

Please create the following exercises in .rmd format, publish to rpub and submit both the .rmd file and the rpub link.

1. Write a loop that calculates 12-factorial

res <- 1 # predefine vector to concatenate result into res
for (i in 1:12) {
  if(i == 1) res <- 1
  else {
    res <- res * i
  }
  cat(i, "!:", res, "\n")
}

## 1 !: 1 
## 2 !: 2 
## 3 !: 6 
## 4 !: 24 
## 5 !: 120 
## 6 !: 720 
## 7 !: 5040 
## 8 !: 40320 
## 9 !: 362880 
## 10 !: 3628800 
## 11 !: 39916800 
## 12 !: 479001600

2. Show how to create a numeric vector that contains the sequence from 20 to 50 by 5.

n_vec <- seq(20, 50, 5)
print(n_vec)

## [1] 20 25 30 35 40 45 50

is.vector(n_vec)

## [1] TRUE

3. Create the function “factorial” that takes a trio of input numbers a, b, and c and solve the quadratic equation. The function should print as output the two solutions.

q_func <- function(a,b,c){
  if (a == 0) {
    print("equation not quadratic")
  }
  
  q_delta <- (b^2 - 4*a*c)
  if(q_delta > 0) {
    sol1 <- (-b + sqrt(q_delta)) / (2 * a)
    sol2 <- (-b - sqrt(q_delta)) / (2 * a)
    return(paste("equation has 2 solutions as follows:", sol1, ",", sol2))
  } else if (q_delta == 0){
    sol1 <- -b / (2*a)
    return (paste("equation has 1 solution:", sol1))
  } else {
    sol1 <- complex(real = -b / (2 * a), imaginary = sqrt(-q_delta) / (2 * a))
    sol2 <- complex(real = -b / (2 * a), imaginary = - sqrt(-q_delta) / (2 * a))
    return(paste("equation has 2 solutions as follows:",sol1, ",", sol2))
  }
}

q_func(1,-3,-5)

## [1] "equation has 2 solutions as follows: 4.19258240356725 , -1.19258240356725"

q_func(1,3,5)

## [1] "equation has 2 solutions as follows: -1.5+1.6583123951777i , -1.5-1.6583123951777i"

q_func(0,3,5)

## [1] "equation not quadratic"

## [1] "equation has 2 solutions as follows: NaN , -Inf"