chi(a,x,b)*f(x)
which can be evaluated within the program, or at the entry line. We define the function within the
program like this:
chi(1,x,2)*x^2→g(x)
this works, as a function
and not like this:
chi(1,x,2)*x^2→g
this DOES NOT work, as an expression
The second example results in an Undefined variable message if we try to evaluate g at the entry line.
If you want g(x) to be a local function, you must declare g with the Local command.
[7.49] Read and write text variables
There are no built-in commands or functions to read or write the contents of text variable, but
Bhuvanesh Bhatt has written two flexible C routines to fix that: TxtWrite() and TxtRead(). Get them,
along with documentation, at http://tiger.towson.edu/~bbhatt1/ti/.
From Bhuvanesh' documentation:
Syntax:
TxtWrite(expression_or_string,"varname","write_mode"[,str_format])
If you wish to prevent evaluation or auto-simplification of the expression, input it as a string. To insert a
newline, just input a blank string.
The writing mode write_mode can be:
"w" or "write" if you want to create a new text variable or overwrite an existing one
"a" or "append" if you want to append to an existing text variable
str_format should be:
0 (default) if strings should be written without quotation marks
1 if quotation marks should be added.
TxtRead("varname")
TxtRead() returns the entire text variable as a list of strings. Do not try to read anything other than a
Text variable. The maximum number of characters per line for TxtRead() is 512.
Example:
TxtWrite("Here is an expression","test","write")
TxtWrite(x^2+2,"test","append")
TxtWrite("Let's try a string with quotes","test","append",1)
Now the text variable test in the current folder will contain:
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