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In this guide, we will discuss Fortran Intrinsic Functions. Intrinsic functions are some common and important functions that are provided as a part of the Fortran language. We have already discussed some of these functions in the Arrays, Characters and String chapters.

Intrinsic functions can be categorised as −

• Numeric Functions
• Mathematical Functions
• Numeric Inquiry Functions
• Floating-Point Manipulation Functions
• Bit Manipulation Functions
• Character Functions
• Kind Functions
• Logical Functions
• Array Functions.

We have discussed the array functions in the Arrays chapter. In the following section we provide brief descriptions of all these functions from other categories.

In the function name column,

• A represents any type of numeric variable
• R represents a real or integer variable
• X and Y represent real variables
• Z represents complex variable
• W represents real or complex variable

Numeric Functions

Example

program numericFunctions
implicit none  

   ! define constants  
   ! define variables
   real :: a, b 
   complex :: z
   
   ! values for a, b 
   a = 15.2345
   b = -20.7689
    
   write(*,*) 'abs(a): ',abs(a),' abs(b): ',abs(b)   
   write(*,*) 'aint(a): ',aint(a),' aint(b): ',aint(b) 
   write(*,*) 'ceiling(a): ',ceiling(a),' ceiling(b): ',ceiling(b)   
   write(*,*) 'floor(a): ',floor(a),' floor(b): ',floor(b)  
    
   z = cmplx(a, b)
   write(*,*) 'z: ',z   
   
end program numericFunctions

When you compile and execute the above program, it produces the following result −

abs(a): 15.2344999   abs(b): 20.7688999    
aint(a): 15.0000000  aint(b): -20.0000000    
ceiling(a): 16  ceiling(b): -20
floor(a): 15  floor(b): -21
z: (15.2344999, -20.7688999)

Mathematical Functions

Example

The following program computes the horizontal and vertical position x and y respectively of a projectile after a time, t −

Where, x = u t cos a and y = u t sin a – g t2 / 2

program projectileMotion  
implicit none  

   ! define constants  
   real, parameter :: g = 9.8  
   real, parameter :: pi = 3.1415927  
   
   !define variables
   real :: a, t, u, x, y   
   
   !values for a, t, and u 
   a = 45.0
   t = 20.0
   u = 10.0
   
   ! convert angle to radians  
   a = a * pi / 180.0  
   x = u * cos(a) * t   
   y = u * sin(a) * t - 0.5 * g * t * t  
   
   write(*,*) 'x: ',x,'  y: ',y   
   
end program projectileMotion

When you compile and execute the above program, it produces the following result −

x: 141.421356  y: -1818.57861  

Numeric Inquiry Functions

These functions work with a certain model of integer and floating-point arithmetic. The functions return properties of numbers of the same kind as the variable X, which can be real and in some cases integer.

Floating-Point Manipulation Functions

Bit Manipulation Functions

Character Functions

Kind Functions

Logical Function

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