[kepler-users] add a complex formula on Kepler - group expressions?

[Karen Tang]

Hi Matt,

Thanks for your help, the expression component works for my calculation. 
Because  my calculation formula  is long and includes 14 constants and 3 
parameters(T, P, S), I divided it into 6 expressions. Currently I have 
all 6 expressions on my workflow. But I am thinking the workflow will be 
more user friendly if I can put these expression actors into one 
composite actor. Am I on the right track? If yes, please give me some 
instructions. If not, what is the best way to do it? Please advise.

To make it clear, here is the expressions:

    * Oxygen:    V1*Oxsat*exp(Pcor*P) -- final output
    * V1:            exp(ATa+S*BTa)
    * Oxsat:        Soc*(V+Voffset)*exp(Tcor*T)
    * ATa:          a1+a2*(100/Ta)+a3*log(Ta/100)+a4*(Ta/100)
    * BTa:          b1+b2*(Ta/100)+b3*pow((Ta/100),2) 
    * Ta:            T0+T

Regards,

Karen

Matthew Jones wrote:

> Hi Karen,
>
> You probably will want to use one of the expression actors to 
> calculate a complex formula.  Your main choices are:
>
> Expression: allows arithmetic and statistical operations on data, 
> including power functions and logarithms, that can be expressed as a 
> single statement
>
> RExpression: allows scripts of arbitrary complexity to be run on the R 
> System for statistical computing, including simple arithmetic, vector 
> and matrix operations, and complex statistical operations.  R is a 
> full-featured scientific computing language.
>
> MatlabExpresion: similar to the RExpression, but obviously depends on 
> the Matlab system for its execution
>
> Any of these systems should be able to do what you want. To use these, 
> you just drag the appropriate actor to the canvas, add named input 
> ports, and then create the expression referring to those named ports. 
> For example, if you created input ports with names "x" and "y" you 
> could write an expression like this:
>
> log(x) + log(y)
>
> and the output will be emitted on the output port.  With the 
> RExpression actor you also create named output ports to map your 
> script variables to the appropriate outputs.
>
> Hope this helps.
>
> Matt
>
> Karen Tang wrote:
>
>> Hi,
>>
>> I am new in Kepler and  I need to have a complicated formula in the 
>> workflow. The formula should take three inputs (web services' 
>> outputs), do a complex calculation (including exponent, logrithm) 
>> then generate a single value.
>>
>> How can I add the formula in Kepler? Do I need to have this in a Java 
>> class, then do it follow steps listed in your archived message 
>> (http://mercury.nceas.ucsb.edu/ecoinformatics/pipermail/kepler-users/2006-March/000068.html)? 
>> I couldn't succeed. Can you give more detailed instructions? An 
>> example will be great.
>>
>> My goal is to enable users(ocean scientists around the world) use 
>> workflows I created. I am using Windows XP.
>>
>> Thanks in advance.
>>
>> Karen
>>
>>  
>>  
>>
>>
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>