test for a specified function
hasfun(e, f, x)
The hasfun command searches an expression e for the function f, or, if f is a list or set of names (of functions), then hasfun searches e for any one of these functions. It returns true if it finds one, false otherwise.
If the third optional argument x is specified, the hasfun function tests if the expression e has function(s) f of x, in the sense that x occurs in one or more arguments of the call to f. A typical application is in integration where you might want to test if the integrand has a special function of a variable x.
For a positive match, x has to occur as an exact subexpression as defined by Maple's op function. See has for examples of what this means.
If the subexpression x that needs to occur in the arguments to f is a list or set, it needs to be enclosed in a list or set itself, otherwise hasfun will search for the members of x only.
e ≔ sin⁡x+ⅇ3⁢y+1
The function name f can be any expression.
e ≔ D⁡x⁡t−x⁡t
The required subexpression x can also be any expression, but it needs to occur as a subexpression as defined by Maple's op function. Below, x+y is not a subexpression of x+y+z.
e ≔ g⁡2⁢f⁡x+y+z−2
If the subexpression you are looking for is a list or set, you need to enclose it in a list or set itself. The first calling sequence looks for the variables k or m occurring; the second for the list k,m; and the third for the list m,n:
e ≔ 1+Hypergeom⁡m,n,,z
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