title: How to implement factorial function into code?
body: <p>So I am using the taylor series to calculate sin(0.75) in fortran 90 up until a certain point, so I need to run it in a do while loop (until my condition is met). This means I will need to use a factorial, here's my code:</p>
  
  <pre><code>program taylor
  implicit none
  real :: x = 0.75  
  real :: y
  integer :: i = 3
  do while (abs(y - sin(0.75)) &gt; 10.00**(-7)) 
   i = i + 2
   y = x - ((x**i)/fact(i))
   print *, y
  end do
  end program taylor
  </code></pre>
  
  <p>Where i've written fact(i) is where i'll need the factorial. Unfortunately, Fortran doesn't have an intrinsic ! function. How would I implement the function in this program?</p>
  
  <p>Thanks.</p>