Hi, 

Please do the following:

1) Save as Math Library of Pega-Rules ruleset into your custom ruleset and save the rule.

2) Check Library ready to be compiled? checkbox and click on 'Generate Library' button.

3) Create a function with name Power with two input parameters of string type, make output data type as 'double' and usage type as 'Output Formatting'.

4) If we want to calculate POWER(4,3); here in this example I am taking Input1 as 4 and Input2 as 3. So, under java tab give the below expression:

Double myD = new Double(input1);

Double myD1 = new Double(input2);
double d = myD.doubleValue();

double d1 = myD1.doubleValue();
return Math.pow(d, d1);

If you have any doubts, please let me know.

Thanks,

Ranz