Question

Please answer the following by coding in R with comments ! Thank you!!!

Evaluation of a square root is achieved using the sqrt() function, but a warning will be issued when the argument is negative. Consider the following code which is designed to test whether a given value is positive before checking whether the square root of the value is less than 5.

testValue <-7

(testValue > 0) & (sqrt(testValue) < 5)

## [1] TRUE

testValue <--7

(testValue > 0) & (sqrt(testValue) < 5)

## Warning in sqrt(testValue): NaNs produced

## [1] FALSE

Modify the code so that it continues to give the correct answer but without the warning.

Answer 1

Let's start with understanding the syntax of sqrt() function in R programming language, the syntax is shown below -

sqrt(numeric_expression)   # Return type is integer

where, numeric_expression can be a positive or negative value.

• When it is a positive value, the sqrt function returns the square root of given value.
• When it is a negative value, the sqrt function returns NaN (Not a Number).

Keeping this in mind, let's modify the code to get rid of warning.

Modified code :

testValue <-7

if (testValue > 0){   # when testValue>0
if(sqrt(testValue) < 5)
{
TRUE # when testValue>0 and sqrt(testValue)<5
}
else
{
FALSE # when testValue>0 but sqrt(testValue)>5
}
} else {
FALSE # when testValue<0
}

## [1] TRUE

testValue <--7

if (testValue > 0){ # when testValue>0
if(sqrt(testValue) < 5)
{
TRUE # when testValue>0 and sqrt(testValue)<5
}
else
{
FALSE # when testValue>0 but sqrt(testValue)>5
}
} else {
FALSE # when testValue<0
}

## [1] FALSE

CONCLUSION :

Using if-else conditional statements, it is easy to get the desired output for various test conditions. This modified code uses nested if-else statements to check each possible outcome of the given condition and prints the valid output.