Exponentiation Not Working???

[Easy Rider]

I'm using this:

(Inches + Feet * 12)*(Inches + Feet * 12)

in a calculated field expression on a Dialog control because the exponentiation operators:

(expression)**2 or (expression)^2

just didn't work.

What am I doing wrong?
Is it me or is it Alpha5?

[Steve Workings]

Re: Exponentiation Not Working???

Try this:

(Inches + (Feet * 12))*(Inches + (Feet * 12))

[Easy Rider]

Re: Exponentiation Not Working???

Thanx, but that's not it:

Arithmetic Operator Precedence

An expression can include multiple arithmetic operators. Use parentheses to control the order in which the expression is evaluated. Alpha Five uses the following order of precedence when evaluating expressions:

Operations enclosed in parentheses

Exponentiation (^ or **)

Multiplication and division (*, /)

Addition and subtraction (+, �)

Including operators in order according to their precedence allows parentheses to be implied when combining operations. For example, the expression 3 + 5 * 4 is equivalent to 3 + (5 * 4) since the multiplication operator has a higher precedence than the addition operator.

[Steve Workings]

Re: Exponentiation Not Working???

Well, then I guess I don't understand your question:

inches = 0
feet = 1
?(Inches + (Feet * 12))*(Inches + (Feet * 12))
= 144

inches = 1
?(Inches + (Feet * 12))*(Inches + (Feet * 12))
= 169

feet = 2
?(Inches + (Feet * 12))*(Inches + (Feet * 12))
= 625

[Pat Bremkamp]

Re: Exponentiation Not Working???

If feet and inches are fields in your dialog, then they are character values. you need to convert them to numeric, then back to string. Normally, javascript doesn't care and does the conversion for you, but in this case, I believe it sees inches as character and is trying to concatenate.

does just inches+feet*12 work by itself?

If not, try
val(inches)+val(feet)*12

If that works, then you can square it.

Pat

[Steve Workings]

Re: Exponentiation Not Working???

Good catch Pat. I was focused on the math and hadn't paid enough attention to where the values were established.

[Easy Rider]

Re: Exponentiation Not Working???

Guys:
Thanx, for all your help, but we still do not have the answer.

Here is the whole, working expression:

Round(Pounds * 703.0696 / (Inches + Feet * 12) * (Inches + Feet * 12),1)

The result matches other sources, so the math is right.
BTW: This is the formula for Body Mass Index.

Pounds, Feet and Inches are all local, numeric, textbox fields, in the dialog.
If I try to say "val(inches), etc." the expression stops working.
If I try to say "(Inches + Feet * 12)^2", it also stops working.
If I try to say "(Inches + Feet * 12)**2", it also stops working.

In a calculated field expression:
It seems, that Alpha5 knows to convert these fields to numbers.
It also seems, that fully qualified field names are not necessary.

Why doesn't the exponentiation operator work???

[MikeC]

Re: Exponentiation Not Working???

E,
either way it seems to work in the interactive---just going by what has been stated here I messed around and got both numeric and character values to come out using both ^ and ** . Unless you cannot test such things in the interactive editor????.....

Regardless, try something VERY simple to see how it comes out....then build on that once it is working---I mean as simple as Pounds*10 even. Then build on it....easiest way to figure out where the problem lies. Also, just because the operands are supposed to work in the order stated, why take the chance or why not make certain that this is NOT the cause??

dim pounds as n
dim inches as n
dim feet as n
dim result as n
result=0
pounds=10
inches=10
feet=10

result=Round((Pounds * 703.0696)/ ((Inches + Feet * 12) * (Inches + Feet * 12)),1)
?result
= 0.4

result=round(Pounds * 703.0696 / (Inches + (Feet * 12))^2,1)
?result
= 0.4

result=round(Pounds * 703.0696 / (Inches + (Feet * 12))**2,1)
?result
= 0.4
''================================================================

dim pounds as c
dim inches as c
dim feet as c
dim result as n
result=0
pounds="10"
inches="10"
feet="10"

result=Round((val(Pounds) * 703.0696)/ ((val(Inches) + val(Feet) * 12) * (val(Inches) + val(Feet) * 12)),1)
?result
= 0.4

result=round(val(Pounds) * 703.0696 / (val(Inches) + (val(Feet) * 12))^2,1)
?result
= 0.4

result=round(val(Pounds) * 703.0696 / (val(Inches) + (val(Feet) * 12))**2,1)
?result
= 0.4

[Easy Rider]

Re: Exponentiation Not Working???

Mike:

WOW! That's one tall, skinny, anorexic person!

Thanx for giving it a try.

The exponentiation operator may work in straight XBasic but apparently NOT in a field calculation expression of a dialog. I wonder if this is just not implemented in the interpreter. That would make it a BUG that should be fixed.

EZR

[Al Buchholz]

Re: Exponentiation Not Working???

Exponentiation doesn't work in a v8 dialog either.

Submit a bug report with a simple example, please.

[JerryBrightbill]

Re: Exponentiation Not Working???

I'm using this:

in a calculated field expression on a Dialog control because the exponentiation operators:

(expression)**2 or (expression)^2

just didn't work.

What am I doing wrong?
Is it me or is it Alpha5?

If you are entering this in the "calculated field expression" property under "Control Settings" for a textbox, any code in that expression must be valid JavaScript. That code runs only on the client computer and can not use any xbasic functionality, just JavaScript. Alpha Five does provide some JavaScript functions such as alltrim() that behave in a similar manner to the equivalent xbasic function, but the there is no built-in JavaScript support for exponentiation. JavaScript will not recognize ^ or ** as these as xbasic operators.

[Easy Rider]

Re: Exponentiation Not Working???

xbasic operators.

Sounds like Alpha5 has room for improvement.
Thank you for answering this question for us.

I don't know JavaScript. Where can I get a tutorial guide/reference?

I could use a good book on Basic too...

[Doug Page]

Re: Exponentiation Not Working???

Sounds like Alpha5 has room for improvement.
Thank you for answering this question for us.

You mean that Alpha has more room to fix all the problems of the other web stuff!

I don't know JavaScript. Where can I get a tutorial guide/reference?

http://www.w3schools.com/JS/default.asp

This is a quick start. Of course, Google is your friend. :)

I could use a good book on Basic too...

I will make the assumption you mean XBASIC not Basic. Good documents and tutorials are included with Alpha.

[Eavan Chambliss]

Re: Exponentiation Not Working???

Since the calculated field expression on a Dialog control is being converted to Javascript, you can use Javascript functions - the expression convert is setup to recognize some basic Alpha functions, and convert them to there Javascript equivalents. The Javascript math function for "x to the power of y" is "Math.pow(x,y)". Therefore, if you create a dialog with three fields (all specified as numbers), named: "feet", "inches", and "sqInches"; and then set the calculated field expression of "sqInches" to "Math.pow((inches+(feet*12)),2)", you'll get the correct number in "sqInches".

This is a pretty good place to general Javascript info: http://www.w3schools.com/jsref/default.asp.

Eavan Chambliss

[Easy Rider]

Re: Exponentiation Not Working???

Thank you, Eavan:

I was just about to try and write my own "Power(x,n)" function. It would simply be a loop to do the multiplication n-1 times. This is what I think it would look like:

function Power(base, exponent)
{
var result = 1;
for (var count = 0; count < exponent; count++)
result *= base;
return result;
}

QUESTION: Could this function be defined, somewhere in my application, so that it could be called by the field calculation expression?
could it be defined and called IN the field calculation expression?

Thanx
EZR