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Fortran 95 Help ( Compiling errors)

  1. Sep 28, 2009 #1
    Hello all, I'm kinda stuck with this fortran 95 program I have to write. It is an Infinite Series of SIN.

    ! Data Dictionary
    REAL :: x ! Measurement of angle in degrees
    REAL :: result ! facilitates addition of the functions
    REAL :: f_x ! function defining the series
    REAL :: rad_x ! Radians equivalent of x
    REAL :: int_value ! Intrinsic function value of sin
    REAL, PARAMETER :: PI = 3.141593 ! universal ratio of circle's diameter
    INTEGER :: n ! Counter
    INTEGER :: fac ! factorial calculation

    ! User Input of X
    WRITE (*,*) 'Input degrees'
    READ (*,*) x
    ! Convert to Radians
    rad_x = x *(PI/180)
    ! Defining Base values for addition of LOOPs
    result = 0.0
    fac = 0
    ! Start of DO LOOP
    DO n = 1, 10
    fac = (2n - 1) *n
    f_x = (-1.0**(n-1))*((rad_x**(2n-1))/(fac))
    result = f_x + result
    END DO
    ! Calcualte INtrinsic value of SIN
    int_value = SIN(rad_x)
    ! Display information
    WRITE (*,*) 'Intrinsic SIN function value', int_value
    WRITE (*,*) 'Calculated value of SIN', result
    ! Finish Up
    END PROGRAM infinite_series

    And I receive the following errors from the compiler

    In file infinite.f95:35

    fac = (2n - 1) *n
    Error: Expected a right parenthesis in expression at (1)
    In file infinite.f95:36

    f_x = (-1.0**(n-1))*((rad_x**(2n-1))/(fac))
    Error: Expected a right parenthesis in expression at (1)

    The "1" is actually under the 2 in (2n-1) but it wont stay put in the post.

    I'm trying to compile to see if the program even works but I need to get past this first. Thank you for any help

    After about a couple hours of racking my brain I discovered I was missing the multiply operator between the 2 and n. fail

    Now the program compiles but I'm having issues with getting the factorial part of the work properly. I can't seem to figure out how to get it to multiply properly within the DO loop. If I separate the two, I can get the factorial to work, but I will not get the equation to work. argh!
    Last edited: Sep 29, 2009
  2. jcsd
  3. Sep 29, 2009 #2


    User Avatar
    Science Advisor

    Took me a minute too...

    2n needs to be 2*n
  4. Sep 29, 2009 #3
    Indeed. Quick question, now if I need help coding, do I make a new post in the homework help section or something or another? I can't get the factorials right.
  5. Sep 29, 2009 #4


    Staff: Mentor

    I think either place would be fine: here or in the Engineering branch of the homework help forum. Start a new thread, though.
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