R_firstweek_homework1

#1 Write a loop that calculates 12-factorial.

x <-1 #define vector first

for (i in 1:12)
{ 
  if(i == 1) x <- 1
  else 
  {
    x <- x * i;
  }
  cat(i,"!=", x, "\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

## The above code helps you to find the factorials from 1 to 12.

## The code below helps you to find the factorial of number 12.  
## The question is little unclear so I have put two different codes for this question.

factorial<- function(a){
  x <-1
  for  (i in 1:a)
  {
    x <- x*((1:a)[i])
  } 
  print(x)
}
factorial(12)

## [1] 479001600

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

numVector <- as.numeric(c(seq(20,50,5)))
print(numVector)

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

##

#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.

QuadFunction <- function(a, b, c) 
{
  numberSqrt <- b^2 - 4*a*c
  if(numberSqrt > 0) 
  {
    x1 <- (-b + sqrt(b^2 - 4*a*c)) / (2*a)
    x2 <- (-b - sqrt(b^2 - 4*a*c)) / (2*a)
    x <- c(x1, x2)
    x
  } 
  else if (numberSqrt == 0) 
  {
    x <- -b/(2*a)
    x
  } 
  else 
  {
    "Denominator is less than 0. Sorry, NO RESULTS."
  }
}

QuadFunction(1, 5, -8)

## [1]  1.274917 -6.274917