Fortran 95 Help ( Compiling errors)

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Discussion Overview

The discussion revolves around a Fortran 95 program intended to calculate an infinite series of the sine function. Participants address compiling errors encountered in the code, particularly related to the syntax for multiplication and the calculation of factorials within a loop.

Discussion Character

  • Technical explanation
  • Homework-related

Main Points Raised

  • The initial code contains syntax errors due to the absence of a multiplication operator between the constants and variables, specifically in the expressions "2n" and "2n-1".
  • One participant identifies the need for the multiplication operator and successfully compiles the program after making the correction.
  • There are ongoing issues with correctly implementing the factorial calculation within the DO loop, which remains unresolved.
  • A participant inquires about the appropriate forum section for further coding assistance, suggesting that either the current thread or a new one in the homework help section could be suitable.

Areas of Agreement / Disagreement

Participants generally agree on the need for the multiplication operator in the code. However, the discussion regarding the factorial calculation remains unresolved, with no consensus on how to implement it correctly.

Contextual Notes

The discussion highlights limitations in the original code related to syntax and the factorial calculation, but does not resolve the specific implementation issues within the DO loop.

shadow1768
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Hello all, I'm kinda stuck with this fortran 95 program I have to write. It is an Infinite Series of SIN.

IMPLICIT NONE
!
! 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
!
! calculate 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
1
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))
1
Error: Expected a right parenthesis in expression at (1)

The "1" is actually under the 2 in (2n-1) but it won't 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:
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Took me a minute too...

2n needs to be 2*n
 
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.
 
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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