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Homework Help: Power series with subprograms Fortran 77 HELP

  1. Apr 9, 2012 #1
    1. The problem statement, all variables and given/known data
    The power series
    1 + x + (X^2)/2! + (x^3)/3! +....(to infinity)= (x^k)/k!
    converges to e^x for all values of x. Write a function subprogram that uses this series to calculate values for e^x to five-decimal-place accuracy (i.e. using terms up to the first one that is less than 10^-5 in absolute value) and that uses a function subprogram to calculate factorials. Use these subprograms in a main program to calculate and print a table of values for the function
    cosh(x) = (e^x + e^-x)/2
    and also the corresponding values of the library function COSH for x = -1 to 1 in increments of .1


    3. The attempt at a solution
    c Print the table heading
    100 FORMAT(3X, A7, 5X, A16, 2X)
    PRINT 100, 'COSH(X)', 'LIBRARY COSH(X)'
    PRINT *, '==============================='

    c ===========================================================
    REAL FUNCTION COSH (G)
    REAL G
    DO 80 G = -1., 1., .1
    COSH = COSH (G)
    80 CONTINUE
    END

    c =============================================================
    REAL FUNCTION HCOSN (POWER)
    REAL POWER

    HCOSN = (POWER + (1/POWER))/2

    END
    c ==============================================================
    REAL FUNCTION POWER (X,I)

    INTEGER FACTOR, I
    REAL X

    DO 20 X= -1., 1., .1
    POWER = (X**I)/FACTOR
    20 CONTINUE

    END

    c ===============================================
    INTEGER FUNCTION FACTOR(N)

    INTEGER N, I

    FACTOR = 1
    DO 10 I = 2, N
    FACTOR = FACTOR * I
    10 CONTINUE

    END
    c ==============================================================

    130 FORMAT (3X, F5.5, 7X, F5.5)
    PRINT 130, HCOSN, COSH

    PAUSE
    END


    I keep getting a ton of errors. Am I setting up the structure of the DO X=-1, 1, .1 with the functions right?
     
  2. jcsd
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