Automation Direct function

[Brian C]

I am using Koyo DL06 PLC
Automation direct 5.3
try to calculate 2 ^ 1.55 ( 2 to the power of 1.55 )
I use this in the flow rate calculation, however, AD do not have the power function, all they have is square root function.
Folks, any work around or tricks. Thanks.

[bernie_carlton]

2^1.55 = 2.9281713918912508413872626586825

It would be a constant, why calculate it?

[ajsimione]

A quick web search of how to solve decimal exponents should point you in the correct direction for simplification of this problem.
A hint to get you started is to think of this as two exponents to solve, i.e. 2^1 x 2^0.55. When solving the decimal portion you'll need to convert it to a fraction in lowest terms and use the laws of exponents to finish it off. Don't want to do it all for you. ;-)

I see Bernie is faster with a better solution.

[Brian C]

Sorry about the confusion, 2 is just an example. It is actually a variable. I am actually have problem with the 2^0.55 portion. 0.5 is fine, I can use the square root function, but 0.55 .....

[bernie_carlton]

So you mean x^1.55 - then you'll need to follow ajsimione's advice.

[Brian C]

Thanks for the hints, but I am still stuck.
X ^ 0.55 = X ^ 11/20 = ( 20√ X) ^ 11
So sad, DL06 does not have 20√ function and the power function :.(

[Lancie1]

(20√ x) ^ 11 =
(20 * √ x) * (20 * √ x) * (20 * √ x) * (20 * √ x) *
(20 * √ x) * (20 * √ x) * (20 * √ x) * (20 * √ x) *
(20 * √ x) * (20 * √ x) * (20 * √ x)

[bernie_carlton]

lancie - your rewriting of (20√ x) as (20 * √ x) makes it look like your are changing the '20th root of x' into '20 times the square root of x'. That makes it confusing. Computing the 20th root of x would still be difficult.

[Brian C]

Thanks Lancie, yes I can multiple 11 times instead, but Bernie is correct. I cannot solve the 20th root of X. No such function in DL06 :-(

[L D[AR2,P#0.0]]

What is your min/max range for x ?
Is a look up table a possibility ?

[Lancie1]

My old 5th grade math teacher taught me that (20√x) = 20 times √x.

Now the 20th root of X = X^1/20 = x^0.05

I suppose it was just sloppy symbol writing.

[Brian C]

Thanks for the attempt, but I am still stuck on x^0.05.
Actually I am using the flow measurement well method for calculating the flow rate, look up table is not an option.
For DL06, they only have add, subtract, multiple, divide, sin, cos, tan and sqrt function. :-(

[Lancie1]

Brian,

If you are really desperate, you possibly could convert your values to binary values, then use binary shifts (which the DL-06 does have) to perform the power terms. Please don't ask me to convert them for you - I have CRS and am just not able to concentrate enough to do that anymore!

Possible instructions that could be used for binary power operations:

ROTL
ROTR
SHFL
SHFR
INV

[Brian C]

Thanks Lancie, I will try it. Appreciate for your help! :-)

[L D[AR2,P#0.0]]

Repetitive use of the square root will allow to to compute the following terms which you can select to the accuracy you require.