Composite Simpsons method for numeric integration

COMPOSITE SIMPSON's method for numerical calculations and analysis exercises of Numeric Integration.

COMPOSITE SIMPSON's method for numerical calculations and analysis exercises of Numeric Integration. f function is given in terms of a symbolic variable x and as an
inline function. E.g., inline('x^2+2*x-2'). Also, if the function f is trigonometric function, the 4th argument can be entered as
'trigonom' or just 'trig' or 1. X is expected to be in degrees for trigonometric function evaluations. The number of steps NSTEPS has
to be even. upl and lowl are upper and lower limits. NB: A sequential order of limits is unnecessary to follow, 'if' conditions will take care of lower and upper limits accordingly.