HP 39gii Programming Tutorial  Part 8: Functions as Arguments
Apologies for the delay.
In part 8, I will show you several was you can use functions as arguments in programs. First, some pointers to help make the programming experience less daunting:
1. The HP 39gii is not a CAS machine. Everything must be evaluated to a number.
2. Functions are entered either as strings (expressions surrounded by quotation marks) or by the use of the QUOTE command. The QUOTE command can be found by pressing [Math], [ 1 ], [ 2 ]. It may help to store the required equation/function in E#/F# first before running the program, which is the case with PARTDER.
3. When using HP mathematical commands, you may have to store passthrough variables into global variables first. I am not sure why this is true for some commands but not for others.
4. The use of expressions and functions don't always work in programming. Use caution. I have particular trouble with SOLVE and FNROOT in this situation.

Note: Recall there are two ways to store objects, one the store arrow ( →) and the assign operator ( := ). I usually code the latter, but for most applications, either way is acceptable. I use both methods in today's programming examples. And yes, we can use both methods in one program.
Hint: I often test commands and their usage at the Home screen to get a better understanding on how mathematical commands work. I also note their syntax by both using the command and accessing the help menu ([SHIFT] [Views]).

The Program PARTDER
PARTDER takes the partial derivatives of the function f(X,Y) at the point (x, y) and returns a list of the values {df/dx, df/dy}.
PARTDER takes two passthrough arguments:
x = value of x
y = value of y
Define f(X,Y) as a string into E0 outside the program.
EXPORT PARTDER(a,b)
BEGIN
a → A; b →Y; ∂(E0, X=A) → C;
b → B; a → X; ∂(E0, Y=B) → D;
RETURN {C, D};
END;
Examples:
"SIN(X*Y)+Y^2"→E0
PARTDER(π, 1) returns { 1, 1.14159265359 }
QUOTE(X^(2*Y+1))→E0
PARTDER(4,1) returns {48, 177.445678223}
Eddie
This blog is property of Edward Shore. 2013
A blog is that is all about mathematics and calculators, two of my passions in life.
Tuesday, April 23, 2013
HP 39gii Programming Tutorial  Part 8: Functions in Programs
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thanks for this part 8 Hp30gii programming tutorial . I am learning , this will help a lot not just for me but for all the people :)
ReplyDeletehttp://merlenemath.com/
Much appreciated, Jason.
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