Is there a power operator or function in AmigaE standard package? I have looked through all the Beginner's Guide and haven't found one.

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@r-tea

Did you look for a function named pow or Pow?

Update: bad news.

Quote:

Pow() returns a raised to the power b. This procedure was not present in AmigaE.

http://cshandley.co.uk/portable/StandardFunctionality.html

Last edited by bison on 05-May-2018 at 08:04 PM.

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@bison

Of course. I have looked for Exp(onent) as well as for "^" operator but there's none of them.

Maybe anyone knows an external AmigaE (not PortablE or CreativE) math mudule containing some extra functions?

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@r-tea

I worked in tech support for three years, so I never assume anything.

If it's just for integers, you could write your own function. I'm not familiar with AmigaE syntax, but this works in python:

def mypow(x, y):
	result = 1
	while y > 0:
		result *= x
		y -= 1
	return result

Last edited by bison on 06-May-2018 at 04:14 AM.

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@bison

Hmmm?

def mypow(x, y):
    result = 1
    while y > 0:
        result *= x
        y -= 1
    return result

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@broadblues

It's not a matter of remembering -- I never knew that in the first place! For some reason I didn't think I could use HTML in posts, just the square bracket tags. Thanks for the tip. I will try to do better.

But... I won't stop calling it the Idiot Message Board Software until it stops doing that blank post thing that happens every now and again.

Last edited by bison on 06-May-2018 at 03:35 AM.

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@bison

This will be slow. You guys might want to look up fast exponentiation. That said, none of these methods work if he needs a non-integral power.

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Thank you guys.
Actually I need powering only for few values of a single byte [128, 64, 32,16, 8, 4, 2, 1]. Then I realised that I can easily workarond that problem by simply providing that values in an array or list (it's AmigaE). Finally I managed it w/o powering.

BTW, its for some enhancements in new, upcoming Hexaco toy/tool located on Aminet

Last edited by r-tea on 06-May-2018 at 06:49 PM.

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@r-tea

Faster and smarter

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@r-tea

You can use the mathieeesingbas.library. There is Fpow() I think. I have used it a few times. Of course, these are all float functions. Don't think you even need to open the library to use the functions since you will anyway need an '!' somewhere in the code, which will make AmigaE to open it for you.

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@simplex

Quote:

This will be slow.

Yes, you are right.

My strategy is to start simple and only optimize what proves to be unacceptably slow. This practice comes from having to maintain my own code.

@r-tea

I like your solution. It's simple and fast.

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"Unix is supposed to fix that." -- Jay Miner

@r-tea

Don't you have shift rotate on AmigaE?

That number sequence is power of 2.

you do this in C.

1<<0 = 1
1<<1 = 2
1<<2 = 4
1<<4 = 8
1<<5 = 16

Last edited by NutsAboutAmiga on 06-May-2018 at 10:00 PM.

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@NutsAboutAmiga

I think you mean:

1<<0 = 1
1<<1 = 2
1<<2 = 4
1<<4 = 16 *
1<<5 = 32 *

Last edited by tonyw on 06-May-2018 at 11:57 PM.
Last edited by tonyw on 06-May-2018 at 11:54 PM.

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@NutsAboutAmiga

That works if the left operand is 1, but if its something else, say 2, then you have to handle that as a special case, since 2^0 is 1, not 2.

And of course, in all these methods we're talking about, you have add code to check for integer overflow or shifting the sign bit in twos-complement representation.

I think @r-tea's solution of pre-computing the results is the best solution to the problem is trying to solve.

Update: corrected spelling/grammar errors. If I see any more, I will ignore them and hope it still make sense.

Last edited by bison on 07-May-2018 at 01:26 AM.
Last edited by bison on 07-May-2018 at 01:23 AM.
Last edited by bison on 07-May-2018 at 01:23 AM.

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"Unix is supposed to fix that." -- Jay Miner

@bison

Quote:

My strategy is to start simple and only optimize what proves to be unacceptably slow.

Wise. "Premature optimization is the root of all evil." -- Donald Knuth

That said, the algorithm I linked to is wonderful.

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I've decided to follow an awful lot of people I respect and leave AmigaWorld. If for some reason you want to talk to me, it shouldn't take much effort to find me.