On recording CPU time for each case for the final exam.

One of the requirements of the final exam is to obtain the CPU time used for each different method.

Below I show a template to follow for recording the CPU time per method

You can record the CPU per method, taken at t=0, t=15 and t=30, or just record the CPU time taken at the end, which is at t=30.

Below a simplified fortran template is shown which just records the CPU time at the end of each method.

Use the Fortran function called CPU_TIME() for this. This works on g77 and g95. I did not try it on other Fortran compilers, but it should also work on those as it is a standard function.

To illustrate how to do this, I show below a simple skeleton program with this idea. (Here is the template if you need it source_code )

!*******

!* high level template for MAE 185 final

!*******

PROGRAM MAE185_final

IMPLICIT NONE

INTEGER I

REAL t_start, t_end, cpu_time_used

DO I=1,3

CALL CPU_TIME(t_start) ! get current CPU time

CALL process( I )

CALL CPU_TIME(t_end) ! get current CPU time

cpu_time_used = t_end - t_start

WRITE(*,FMT='(A,I2,A,F10.8)') 'CPU TIME used for case', I, ' = ', cpu_time_used

END DO

END PROGRAM

!**************

!*

!**************

SUBROUTINE process(case_number)

IMPLICIT NONE

INTEGER case_number,I

! other data declaration here...

SELECT CASE(case_number)

CASE(1)

CALL explicit(.....)

CASE(2)

CALL implicit(.....)

CASE(3)

CALL crank_nicholson(.....)

END SELECT

END SUBROUTINE

!**************

!*

!**************

SUBROUTINE explicit(...)

! other data declrations here

t=0

... write solution to file 'exp0.txt' at t=0

DO while (t<=30)

... write solution to file 'exp15.txt' at t=15

... write solution to file 'exp30.txt' at t=30

t= t + delta_t

END DO

END SUBROUTINE