Initial data commit

Task/Call-a-function/Fortran/call-a-function-1.f

@@ -0,0 +1,70 @@
+program main
+implicit none
+integer :: a
+integer :: f, g
+logical :: lresult
+interface
+  integer function h(a,b,c)
+    integer :: a, b
+    integer, optional :: c
+  end function
+end interface
+write(*,*) 'no arguments: ', f()
+write(*,*) '-----------------'
+write(*,*) 'fixed arguments: ', g(5,8,lresult)
+write(*,*) '-----------------'
+write(*,*) 'optional arguments: ', h(5,8), h(5,8,4)
+write(*,*) '-----------------'
+write(*,*) 'function with variable arguments: Does not apply!'
+write(*,*) 'An option is to pass arrays of variable lengths.'
+write(*,*) '-----------------'
+write(*,*) 'named arguments: ', h(c=4,b=8,a=5)
+write(*,*) '-----------------'
+write(*,*) 'function in statement context: Does not apply!'
+write(*,*) '-----------------'
+write(*,*) 'Fortran passes memory location of variables as arguments.'
+write(*,*) 'So an argument can hold the return value.'
+write(*,*) 'function result: ', g(5,8,lresult) , ' function successful? ', lresult
+write(*,*) '-----------------'
+write(*,*) 'Distinguish between built-in and user-defined functions: Does not apply!'
+write(*,*) '-----------------'
+write(*,*) 'Calling a subroutine: '
+a = 30
+call sub(a)
+write(*,*) 'Function call: ', f()
+write(*,*) '-----------------'
+write(*,*) 'All variables are passed as pointers.'
+write(*,*) 'Problems can arise if instead of sub(a), one uses sub(10).'
+write(*,*) '-----------------'
+end program
+
+!no argument
+integer function f()
+f = 10
+end function
+
+!fixed number of arguments
+integer function g(a, b, lresult)
+integer :: a, b
+logical :: lresult
+g = a+b
+lresult = .TRUE.
+end function
+
+!optional arguments
+integer function h(a, b, c)
+integer :: a, b
+integer, optional :: c
+
+h = a+b
+if(present(c)) then
+  h = h+10*c
+end if
+end function
+
+!subroutine
+subroutine sub(a)
+integer :: a
+a = a*100
+write(*,*) 'Output of subroutine: ', a
+end subroutine

Task/Call-a-function/Fortran/call-a-function-2.f

@@ -0,0 +1,4 @@
+      REAL this,that
+      DIST(X,Y,Z) = SQRT(X**2 + Y**2 + Z**2) + this/that !One arithmetic statement, possibly lengthy.
+      ...
+      D = 3 + DIST(X1 - X2,YDIFF,SQRT(ZD2))              !Invoke local function DIST.

Task/Call-a-function/Fortran/call-a-function-3.f

@@ -0,0 +1,2 @@
+      H = A + B
+      IF (blah) H = 3*H - 7

Task/Call-a-function/Fortran/call-a-function-4.f

@@ -0,0 +1,25 @@
+      REAL FUNCTION INTG8(F,A,B,DX)	!Integrate function F.
+       EXTERNAL F	!Some function of one parameter.
+       REAL A,B		!Bounds.
+       REAL DX		!Step.
+       INTEGER N	!A counter.
+        INTG8 = F(A) + F(B)	!Get the ends exactly.
+        N = (B - A)/DX		!Truncates. Ignore A + N*DX = B chances.
+        DO I = 1,N		!Step along the interior.
+          INTG8 = INTG8 + F(A + I*DX)	!Evaluate the function.
+        END DO			!On to the next.
+        INTG8 = INTG8/(N + 2)*(B - A)	!Average value times interval width.
+      END FUNCTION INTG8	!This is not a good calculation!
+
+      FUNCTION TRIAL(X)		!Some user-written function.
+       REAL X
+        TRIAL = 1 + X		!This will do.
+      END FUNCTION TRIAL	!Not the name of a library function.
+
+      PROGRAM POKE
+      INTRINSIC SIN	!Thus, not an (undeclared) ordinary variable.
+      EXTERNAL TRIAL	!Likewise, but also, not an intrinsic function.
+      REAL INTG8	!Don't look for the result in an integer place.
+       WRITE (6,*) "Result=",INTG8(SIN,  0.0,8*ATAN(1.0),0.01)
+       WRITE (6,*) "Linear=",INTG8(TRIAL,0.0,1.0,        0.01)
+      END

Task/Call-a-function/Fortran/call-a-function-5.f

@@ -0,0 +1,5 @@
+      TYPE MIXED
+       CHARACTER*12 NAME
+       INTEGER STUFF
+      END TYPE MIXED
+      TYPE(MIXED) LOTS(12000)