evaluate to a name - Maple Help

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evaln - evaluate to a name

Calling Sequence

evaln(expr)

Parameters

expr

-

expression

Description

• 

The evaln function is used to "evaluate to a name" or, more generally, to form an assignable object. The name (assignable object) will not itself be evaluated.

• 

A typical example of its use would be divide(a,b,evaln(t[i])) where i is the index of a for loop.

• 

If the expression is a simple name (i.e. a symbol) then the same effect can be achieved by using single quotes on the name.

• 

evaln can be used on names, subscripts, function calls, and concatenations.

• 

There is also a procedure parameter modifier, evaln, which declares that an argument to a procedure invocation must evaluate to a name.

Thread Safety

• 

The evaln command is thread-safe as of Maple 15.

• 

For more information on thread safety, see index/threadsafe.

Examples

i:=1

i:=1

(1)

evalni

i

(2)

evalna||i

a1

(3)

evalna||1..3

a1,a2,a3

(4)

evalnti

t1

(5)

evalnfi

f1

(6)

dividex2,x,evalnti

true

(7)

ti

x

(8)

If something which does not evaluate to a name is passed to evaln an error is returned

evaln3

Error, illegal use of an object as a name

See Also

:=, assigned, The evaln Modifier, uneval


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