this is a fortran problem.

Part A Tasks

1. Type the following program exactly as shown:

! This program generates a table of the square roots of integers

! in a user-specified range.

program squares

implicit none

integer start, finish, i

! ----------------------------------------------Prompt and Input print*, "Enter the range (two integers) ..."

read*, start, finish

! ----------------------------------------------Validation & Processing

if (start .GT. finish) then

print*, "Invalid: the start must be less than the end value!"

else if (start .LT. 0) then

print*, "Invalid: the range must not have negative values!"

else

do i = start, finish

write(*,*) i, sqrt(i*1.)

end do

end if

! ----------------------------------------------

end

2. Compile the program as you learned in Lab #1.

Experiments

1. When run, the program prompts you to specify a range of positive integers by entering two integers, being the beginning and end of the range. You can enter the two end-points by separating them by a space or a comma or by pressing ENTER. Try: 1,20 and examine the output.

2. Re-run the program and test invalid ranges; e.g. -10, 10 or 10, 2. Note how the program ends with an error message even though its code flows "smoothly"; without end statements in the middle of it.

3. The argument of the square root function looks strange: Why did we have to mutiply i by 1? Experiment, then explain.

Questions

4. Add the following statement before the prompt but after declarations:

open (unit=50, file='sqroot.txt'). Furthermore, change the first asterisk in the write statement (inside the loop) to 50. These changes cause the output of the write statement to be redirected: Instead of appearing on the screen, it goes to the named disk file. Verify this by viewing the generated sqroot.txt file.

Note:

o You can view the file by issuing the following DOS command: type sqroot.txt|more.

o If you prefer to create the file elsewhere on the hard drive; i.e. not in the same directory as the program, prefix the filename by an appropriate path; in Windows: e.g. 'C:\\sqroot.txt' will store it in the root directory of drive C: . (since the backslash character has a special meaning to this compiler, we type two backslashes to escape the special handling). On the Mac: use e.g. '/User//Documents/sqroot.txt'

5. Restore the program back to screen output and modify it so that the square root appears formatted with only two decimals.

6. Modify the program so that it does not generate any output for integers that are multiples of 5. For example, if the range is 1 to 18, then no lines will be printed for 5, 10 nor 15.

Part B Tasks

1. Type the following program exactly as shown:

! ------- The Effects of Compound Interest -------

! This program calculates the value of an investment

! year-by-year to age 65. The investment grows at a

! given interest rate and the same amount is added

! each year.

program Retire

implicit none

integer age, i

real annualAmt, investment, interestRate

print*, "Enter the amount of your annual contribution:"

read*, annualAmt

print*, "Enter the interest rate

read*, interestRate

print*, "Enter your start age: "

read*, age

print*, "Annual contribution is:

print*, "Annual interest rate :

print*, "Your current age is :

print*, "age investment"

investment = 0.0

do i = age+1, 65

! add annual contribution at beginning of the year

investment = investment + annualAmt

! calculate value of investment at end of the year

investment = investment + investment

interestRate / 100

write(*,12) i, investment

12 format(1x, I5, F12.2)

end do

stop

end

2. Compile the program as you learned in Lab #1.

Experiments

3. Run the program with various inputs to study the effect of compound interest.

Questions

4. Modify the program so that the stop age is also an input, and further modify the program that it checks that the start age is less than the stop age and both are greater than zero. The program will continue to compound the investment to age 65, but will stop adding annual contributions after the stop age.

Experiments

5. It is claimed that starting to save early and stopping after several years is better than starting late and saving to age 65. Explore various scenarios to validate or refute this claim. For example, how does starting at age 20 and stopping at age 25 compare to starting at 40 and not stopping until age 65.