For example, a number can be raised to an integer power
Y = X**4 ; Z = X**(-6)Both exponent values , are written directly in the source text.
For real constants, we need to use either decimal point notation or scientific notation (similar to floating point notation base 10: we have a mantissa, followed by an exponent of 10; the expenent is preceded by E)
Y = X + 21.54 or Y = X + 2.154E+1For double precision constants, we always use scientific notation, but now the exponent marker E is replaced by D, from double:
Y = X + 21.54D0 or Y = X + 2.154D+1For complex literal constants we need to specify a (real part, imaginary part) pair. To assign the number we do
Z = ( 2.25, 4.1 )
Logical constants can take one of two values, written as
Q = .TRUE. or Q = .FALSE.
Finally, character literal constants are delimited by single or double quotes
C = 'A' or C = "A"
If the delimiter is part of the string, the convention is to write it twice inside the string, for example
C = 'O''Malley'