7.3.5 Defining a function with history
The as_function_of
command creates a function defined by an expression, even if the desired variable
already has a value.
-
as_function_of takes two arguments:
-
x, a variable.
- exprvar, another variable containing an expression which
itself may involve x.
- as_function_of(exprvar,x)
returns a function defined by the expression that exprvar
contains.
Example
|
(a)->{ return(sqrt(1+a^2)); }
| | | | | | | | | | |
|
Remark.
If the variable b has been assigned several times, the first
assignment of b following the last assignment of a
will be used. Moreover, the order used is the order of validation of
the commandlines, which may not be reflected by the Xcas interface if
you reused previous commandlines.
Example
a:=2:;
b:=2*a+1:;
b:=3*a+2:;
c:=as_function_of(b,a) |
|
(a)->{ return(sqrt(1+a^2)); }
| | | | | | | | | | |
|
So c(x) is equal to 2x+1. But:
a:=2:;
b:=2*a+1:;
a:=2:;
b:=3*a+2:;
c:=as_function_of(b,a) |
|
(a)->{ return(sqrt(2+3*a^2)); }
| | | | | | | | | | |
|
So c(x) is equal to 3x+2.
Hence the line where a is defined must be reevaluated before the good
definition of b.