#CUNY SPS Bridge: R section, Assignment 1
#Name: Chinedu Onyeka
#Date: July 24th, 2021

#Question 1: Write a loop that calculates 12 factorial

get_factorial <- function(n){
  result <- 1
  
  for(i in 1:n){
    result = result * i
  }
  
  print(result)
}

get_factorial(12)

## [1] 479001600

#Question 2: Create a numeric vector that contains the sequence from 20 to 50 by 5
numVec <- c(seq(20,50,5))

numVec

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

#Problem 3: Function that solves a quadratic equation
quadratic_equation <- function(a,b,c){
  #Check if function is quadratic
  if(a==0){
    print('The equation is not a quadratic equation')
  }
  else{
  D <- (b^2 - 4*a*c)
  
  if(D == 0){
    #We have real and equal roots
    x <- (-b/(2*a))
    sprintf('The roots are real and equal. The solution is: %s',x)
  }
  
  else if(D > 0){
    #We have real and different roots
    x1 <- ((-b + D^0.5)/(2*a))
    x2 <- ((-b - D^0.5)/(2*a))
    sprintf('The roots are real and different. The solutions are: %s and %s', x1,x2)
  
  }
  
  else { 
    #We have 2 complex roots
    x1 <- complex(real = -b/(2*a), imaginary = (-D)^0.5/(2*a))
    x2 <- complex(real = -b/(2*a), imaginary = -(-D)^0.5/(2*a))
    sprintf('The two roots are complex. The solutions are: %s and %s', x1,x2)
  }
  }
}

quadratic_equation(1,4,4)

## [1] "The roots are real and equal. The solution is: -2"

quadratic_equation(0,8,4)

## [1] "The equation is not a quadratic equation"

quadratic_equation(1,4,2)

## [1] "The roots are real and different. The solutions are: -0.585786437626905 and -3.41421356237309"

quadratic_equation(1,2,2)

## [1] "The two roots are complex. The solutions are: -1+1i and -1-1i"

quadratic_equation(1,1,1)

## [1] "The two roots are complex. The solutions are: -0.5+0.866025403784439i and -0.5-0.866025403784439i"