R__-Assignment-_Bridge_Week_1.R

# R Bridge Week 1 Assignment
# SPS Cuny - Bridge Program
# Spring 2017

# Duubar E. Villalobos Jimenez
# mydvtech@gmail.com


# 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.


MyFactorialFunction <- function(MyFactorialInput) {
  MyFactorial <- 1
  for (i in 1:MyFactorialInput)
  {
    MyFactorial <- MyFactorial * i
  }
  return(MyFactorial)
}

x <- 12
MyFactorialFunction(x) # 12! Should return 479001600

## [1] 479001600

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


MyNumericVector <- seq(20, 50, by = 5 )
MyNumericVector

## [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.

MyFactorial <- function (a, b, c) {
  MyDiscriminant <- b ^ 2 - 4 * a * c  # Find the Discriminant
  if (MyDiscriminant >= 0)
  {
    MySol1 <- (-b + sqrt(MyDiscriminant)) / 2 * a  # Find First Solution
    MySol2 <- (-b - sqrt(MyDiscriminant)) / 2 * a  # Find Second Solution
  } 
  else # Working Imaginary Solutions
  {
    print(" ***** WARNING THE SOLUTION TO THIS EQUATION IS IN THE COMPLEX GROUP OF NUMBERS ***** ")
    MySol1 <- paste("(",-b ,"+", sqrt(-MyDiscriminant),"i)","/(", 2 * a,")") # Imaginary Solutions
    MySol2 <- paste("(",-b ,"-", sqrt(-MyDiscriminant),"i)","/(", 2 * a,")") # Imaginary Solutions
    if (b == 0) # Simplifying Fractions
    {
      MySol1 <- paste(sqrt(-MyDiscriminant),"i/(", 2 * a,")") # Imaginary Solutions
      MySol2 <- paste(-sqrt(-MyDiscriminant),"i/(", 2 * a,")") # Imaginary Solutions
      if (sqrt(-MyDiscriminant) == a)
      {
        MySol1 <- paste("i","/", 2) # Imaginary Solutions
        MySol2 <- paste("-i","/", 2) # Imaginary Solutions
        if (sqrt(-MyDiscriminant) == 2)
        {
          MySol1 <- paste("i") # Imaginary Solutions
          MySol2 <- paste("-i") # Imaginary Solutions
        }
      }
      if (sqrt(-MyDiscriminant) == 2)
      {
        MySol1 <- paste("i","/", a) # Imaginary Solutions
        MySol2 <- paste("-i","/", a) # Imaginary Solutions
        if (a == 1)
        {
          MySol1 <- paste("i") # Imaginary Solutions
          MySol2 <- paste("-i") # Imaginary Solutions
        }
      }
    }
  }
  if (b >= 0)
  {
    b = paste("+",b)
  }
  if (c >= 0)
  {
    c = paste("+",c)
  }
  # Final Print outs
  OriginalEquation <- paste(a,"x^2",b,"x",c, "= 0")
  print(paste("The original Equation is: ", OriginalEquation))
  print(paste("The first solution is: x1 = ", MySol1))
  print(paste("The second solution is: x2 = ", MySol2))
  if (is.numeric(MySol1) & is.numeric(MySol2))
  {
    MyEquation <- paste("(x +", (-1 * MySol1), ")(x +", (-1 *MySol2), ") = 0")
    
    if (MySol1 == MySol2)
    {
      MyEquation <- paste("(x", -1 * MySol1, ")^2 = 0")
    }
  }
  else
  {
    MyEquation <- paste("(x +", ( MySol1), ")(x +", ( MySol2), ") = 0")
    
    if (MySol1 == MySol2)
    {
      MyEquation <- paste("(x",  MySol1, ")^2 = 0")
    }
  }
  print(paste("The factorized equation will be: ", MyEquation))
#  MySolutionsFrame <- data.frame("Original" = OriginalEquation, "x1" = MySol2, "x2" = MySol1, "Equation" = MyEquation)
#  MySolutionsFrame
}

MyFactorial(10,21,-27)

## [1] "The original Equation is:  10 x^2 + 21 x -27 = 0"
## [1] "The first solution is: x1 =  90"
## [1] "The second solution is: x2 =  -300"
## [1] "The factorized equation will be:  (x + -90 )(x + 300 ) = 0"