小弟有fortran 90的作業，但有一段不支是哪裡錯，
要用array 讀數字：

...

IMPLICIT NONE
!arrays
REAL, DIMENSION(:,: ), ALLOCATABLE :: A, B, C

!VARIABLES
INTEGER :: length, I, J

!main program

!intro message
PRINT "(A)", "this program will solve equations using arrays"
PRINT "(A)", "in form of B=A*C"
PRINT "(A)", "the program will read values from matrix_a.dat"
PRINT "(A)", "and matrix_c.dat to calculate B"
PRINT "(A)", "where users can adjust the size of the matrix"
PRINT "(A)", "pess 'enter' to continue"

!pause till user ready to start
READ *

!ask user to input the size of the array
!and to check if the number is between 1 and 4
DO
PRINT "(A)", "enter the number of equations used:"
READ *,length
IF (length>=1.AND.length<=4) then
EXIT
ELSE
PRINT "(A)", "input error!!!, must between 1 and 4!!!"
END IF
END DO

!setup arrays
ALLOCATE(A(length, length), B(length, 1), C(length, 1))


!open files matrix_a.dat
OPEN (UNIT=10, FILE="matrix_a.dat", STATUS="OLD", ACTION="READ", POSITION="REWIND", IOSTAT=I)
!check to see if matrix_a.dat is open correctly
IF (I/=0) THEN
PRINT "(A)", "error in opening file"
STOP
ELSE
PRINT "(A)", "file open successfully"
PRINT "(A,I1,A,I1,A)", "matrix A has dimensions (", length, ",", length, ")"
END IF

READ *
!read values into arrays A
!outer loop for rows
DO I=1, length
!iner loop for columns
DO J=1, length
READ (UNIT=10, FMT="(F4.2)") A(I,J)
END DO
END DO


...

在做後一段會出現：
end of file on unit 10
program terminated by fatal I/O errer



大家救救我吧。