start adding some array functions

Makefile

@@ -4,7 +4,7 @@
 
 all: stock_prices
 
-stock_prices:
+stock_prices: src/stock_prices.f90
  $(MAKE) --directory=src $@
  cp src/$@ .
 

src/Makefile

@@ -1,7 +1,7 @@
 # stock-prices Makefile
 
 FC = gfortran
-OBJS = mod_io.o
+OBJS = mod_arrays.o mod_io.o
 
 all: stock_prices
 
@@ -16,6 +16,7 @@ stock_prices: stock_prices.f90 $(OBJS)
  $(FC) $< $(OBJS) -o $@
 
 # modules
+mod_arrays.o: mod_arrays.f90
 mod_io.o: mod_io.f90
 
 .PHONY:

src/mod_arrays.f90

@@ -0,0 +1,25 @@
+module mod_arrays
+
+ ! Utility functions that operate on arrays.
+
+ implicit none
+
+ private
+ public :: mean, reverse
+
+contains
+
+ pure real function mean(x)
+ ! Returns a mean of x.
+ real, intent(in) :: x(:)
+ mean = sum(x) / size(x)
+ end function mean
+
+ pure function reverse(x)
+ ! Reverses the order of elements of x.
+ real, intent(in) :: x(:)
+ real :: reverse(size(x))
+ reverse = x(size(x):1:-1)
+ end function reverse
+
+end module mod_arrays

src/stock_prices.f90

@@ -1,21 +1,33 @@
 program stock_prices
 
+ use mod_arrays, only: mean, reverse
  use mod_io, only: read_stock
 
  implicit none
 
  character(len=4), allocatable :: symbols(:)
  character(len=10), allocatable :: time(:)
  real, allocatable :: open(:), high(:), low(:), close(:), adjclose(:), volume(:)
- integer :: i
+ integer :: i, im, n
 
  symbols = ['AAPL', 'AMZN', 'CRAY', 'CSCO', 'HPQ ',&
  'IBM ', 'INTC', 'MSFT', 'NVDA', 'ORCL']
 
- do i = 1, size(symbols)
- call read_stock('data/' // trim(symbols(i)) // '.csv', time,&
+ write(*,*) 'Symbol, Open, Close, Average, Max. growth [%]'
+
+ do n = 1, size(symbols)
+
+ call read_stock('data/' // trim(symbols(n)) // '.csv', time,&
  open, high, low, close, adjclose, volume)
- write(*,*) symbols(i), maxval((close - open) / open * 100)
+
+ open = reverse(open)
+ close = reverse(close)
+
+ im = size(close)
+
+ write(*,*) symbols(n), open(1), close(im), mean(open),&
+ maxval((close - open) / open * 100)
+
  end do
 
 end program stock_prices