How to use Fortran 90 on the Unix computers at Stanford. Basic program structure. Logical expressions. Loops. Arrays. Subprograms. Modules. Derived data types. Many, many more features of Fortran 90. F90 Program StructureF90 Program Structure zA Fortran 90 program has the following form:A Fortran 90 program has the following form: program-name is the name of that program specification-part, execution-part, and subprogram-part are optional. Although IMPLICIT NONEis also opp,tional, this is required in this course to write safe programs. PROGRAMprogram-name Full details of all the items in this tutorial can be found in Fortran 90/95 Explained, by M. Metcalfand J. Reid, (Oxford, 1996), the book upon which it has beenbased. Like all FORTRAN 77 functions(SIN, ABS, etc., but not LEN), these are array valued forarray arguments (i.e. are elemental). Fortran90 Tutorial 8 3. Control Statements Logical operators can be be short-circuiting, as in C, but apparently are not required to be short-circuiting. See the Fortran 77 standard and Fortran bug bites.That is, if expression A is false when evaluating (A .and. B), then expression B might not be evaluated. Similarly, if A is true when evaluating (A .or.B), then B might not be evaluated. Coming from C/C++, Perl, Python, this ambiguity Numeric Functions. It truncates fractional part of A towards zero, returning a real, whole number. It returns a real value, the nearest integer or whole number. It returns the least integer greater than or equal to number A. It converts the real variables X and Y to a complex number X+iY; if Y is absent, 0 is used. Calculate Beta Function NEW. Calculate the cosine and sine integrals using subroutine CISIA NEW. Calculates a specific characteristic value of Mathieu functions using subroutine CVA1. Compute the confluent hypergeometric function M (a,b,x) using subroutine CHGM NEW. Compute the Struve function H0 (x) using subroutine STVH0 NEW. [real] function f(a,g) integer, intent(in) :: a [real :: f] einterface real function g(x) real, intent(in) :: x end function g end interface end function f fu nc tiode in pu ta rm e r e tu nyp , if od xp li ctn erfa b o k define dummy var as function recursive function f(x) a l ow recu si n incr(x) = x + 1 s ta em nfu c io interface int Exercise 6.3. Write a program that allows a user to enter the size of a square matrix. In the program write a subroutine to compute a finite difference matrix. Ensure your output is neatly formatted in rows and columns. So, for a 10 by 10 matrix, we expect output to look like this. gain access to its 'SUBROUTINES', 'FUNCTIONS' and data. Any declared entities in a module that are intended to be used externally can be accessed by Fortran 90's 'USE' statement. The 'USE' statement can be included in any program unit, function or subroutine of a Fortran 90 code. Its syntax can be described in two forms. Tests the binary value of a bit in a specified position of an integer argument. This function uses the standard Fortran 90 bit model defined in The Fortran 90 Handbook. Synopsis. BTEST(I, POS) Arguments. The argument I must be of type integer. The argument POS must be an integer with a value less than or equal to the value BIT_SIZE(I). Return Value FFTW (GPL), which has Fortran 77 and 90 interfaces. I've used it in some simple projects before, and for inverse transforms the only hurdle I It is written for a particular form of a f