Unclassifiable statement in Fortran 95 when declaring function - fortran

Question

I would appreciate some help on this. The point of the program is to take a lower bound, an upper bound, and the number of steps, and then input them into the respective chosen equation to create a matrix that is the length of the steps, that contains the values for for the equation that was chosen. I'm getting an unclassifiable statement at:
array(i)=function1(x)
array(i)=function2(x)
array(i)=function3(x)
I feel like it has something to do with how I declared my function, but I cannot figure out a fix to it. Any help would be appreciated.
PROGRAM stuff1
IMPLICIT NONE
!variables
INTEGER::i,step
REAL::lower,upper,function1,function2,function3,x,q,w,e
CHARACTER(20)::option
REAL,ALLOCATABLE::array(:)
!formats
101 FORMAT(A) !single text element only
102 FORMAT() ! <description>
!-------Variable Definitions-------!
!
!
!
!----------------------------------!
!x= .1(upper-lower)
!<Begin Coding Here>
WRITE(*,101)"Hello User, please select a function to evaluate:"
WRITE(*,101)
WRITE(*,101)"A) f(x)=x^2+2x+4"
WRITE(*,101)"B) f(x)=|x+4|"
WRITE(*,101)"C) f(x)=sin(x)+42"
WRITE(*,101)"Enter A,B,or C"
DO
READ(*,101)option
IF ((option.EQ."A") .OR. (option.EQ."a")) THEN
ELSE IF((option.EQ.'B') .OR. (option.EQ.'b'))THEN
ELSE IF((option.EQ.'c') .OR. (option.EQ.'c'))THEN
ELSE
WRITE(*,*)"Please enter A,B,or C"
CYCLE
END IF
EXIT
END DO
WRITE(*,101)"please enter an lower bound:"
READ(*,*)lower
WRITE(*,101)
WRITE(*,101)"please enter an upper bound:"
READ(*,*)upper
WRITE(*,101)
WRITE(*,101)"please enter a step size"
READ(*,*)step
function1=((x**2)+(2*x)+4)
function2=(abs(x+4))
function3=(sin(x)+42)
ALLOCATE(array(step))
x=lower
DO i=1,step
IF ((option.EQ."A") .OR. (option.EQ."a")) THEN
array(i)=function1(x)
ELSE IF((option.EQ.'B') .OR. (option.EQ.'b'))THEN
array(i)=function2(x)
ELSE IF((option.EQ.'c') .OR. (option.EQ.'c'))THEN
array(i)=function3(x)
END IF
x=x+(upper-lower)/step
END DO
DO i=1,step
WRITE(*,'(4F6.2)')array(i)
END DO
END PROGRAM

Answer 1

These lines
function1=((x**2)+(2*x)+4)
function2=(abs(x+4))
function3=(sin(x)+42)
appear to be three statement functions. This is an obsolescent feature which you should not use, instead you should define functions along the lines
real function one(x)
real, intent(in) :: x
one = x**2 + 2*x + 4
end function one
If you must program like it's 1979 then the correct form for a statement function would be
function1(x)=((x**2)+(2*x)+4)
You have omitted the dummy argument in the definitions, it's no surprise to me that the compiler gets angry and issues that error.

Answer 2

That's not how to define a function in Fortran!
After the END PROGRAM, define your functions like:
real function function1(x)
real,intent(in) :: x
function1=((x**2)+(2*x)+4)
end function
real function function2(x)
real,intent(in) :: x
function2=(abs(x+4))
end function
real function function3(x)
real,intent(in) :: x
function3=(sin(x)+42)
end function
Or, even better, put them into a module!