The arithmetic mean (i.e., average), geometric mean and harmonic mean of a set of n numbers x1, x2, ..., xn are defined as follows:
Since computing geometric mean requires taking square root, it is further required that all input data values must be positive. As a result, this program must be able to ignore those non-positive items. However, this may cause all input items ignored. Therefore, before computing the means, this program should have one more check to see if there are valid items.
Click here to download this program.! ---------------------------------------------------------- ! This program reads a series of input data values and ! computes their arithmetic, geometric and harmonic means. ! Since geometric mean requires taking n-th root, all input ! data item must be all positive (a special requirement of ! this program , although it is not absolutely necessary). ! If an input item is not positive, it should be ignored. ! Since some data items may be ignored, this program also ! checks to see if no data items remain! ! ---------------------------------------------------------- PROGRAM ComputingMeans IMPLICIT NONE REAL :: X REAL :: Sum, Product, InverseSum REAL :: Arithmetic, Geometric, Harmonic INTEGER :: Count, TotalNumber, TotalValid Sum = 0.0 ! for the sum Product = 1.0 ! for the product InverseSum = 0.0 ! for the sum of 1/x TotalValid = 0 ! # of valid items READ(*,*) TotalNumber ! read in # of items DO Count = 1, TotalNumber ! for each item ... READ(*,*) X ! read it in WRITE(*,*) 'Input item ', Count, ' --> ', X IF (X <= 0.0) THEN ! if it is non-positive WRITE(*,*) 'Input <= 0. Ignored' ! ignore it ELSE ! otherwise, TotalValid = TotalValid + 1 ! count it in Sum = Sum + X ! compute the sum, Product = Product * X ! the product InverseSum = InverseSum + 1.0/X ! and the sum of 1/x END IF END DO IF (TotalValid > 0) THEN ! are there valid items? Arithmetic = Sum / TotalValid ! yes, compute means Geometric = Product**(1.0/TotalValid) Harmonic = TotalValid / InverseSum WRITE(*,*) 'No. of valid items --> ', TotalValid WRITE(*,*) 'Arithmetic mean --> ', Arithmetic WRITE(*,*) 'Geometric mean --> ', Geometric WRITE(*,*) 'Harmonic mean --> ', Harmonic ELSE ! no, display a message WRITE(*,*) 'ERROR: none of the input is positive' END IF END PROGRAM ComputingMeans
it will generate the following output. In this input, all data values are positive and none of them is ignored.5 1.0 2.0 3.0 4.0 5.0
Input item 1 --> 1. Input item 2 --> 2. Input item 3 --> 3. Input item 4 --> 4. Input item 5 --> 5. No. of valid items --> 5 Arithmetic mean --> 3. Geometric mean --> 2.6051712 Harmonic mean --> 2.18978071
The output is shown below:6 1.0 2.0 3.0 -4.0 5.0 6.0
Input item 1 --> 1. Input item 2 --> 2. Input item 3 --> 3. Input item 4 --> -4. Input <= 0. Ignored Input item 5 --> 5. Input item 6 --> 6. # of items read --> 6 # of valid items -> 5 Arithmetic mean --> 3.4000001 Geometric mean --> 2.82523465 Harmonic mean --> 2.27272725
We shall get the following output. The program correctly detects there is no valid data values and displays a message.4 -1.0 -2.0 0.0 -3.0
Input item 1 --> -1. Input <= 0. Ignored Input item 2 --> -2. Input <= 0. Ignored Input item 3 --> 0.E+0 Input <= 0. Ignored Input item 4 --> -3. Input <= 0. Ignored ERROR: none of the input is positive