Slope requires a real as parameter 2?
- by Dave Jarvis
Question
How do you pass the correct value to udf_slope's second parameter type?
Attempts
CAST(Y.YEAR AS FLOAT), but that failed (SQL error).
Y.YEAR + 0.0, but that failed, too (see error message).
slope(D.AMOUNT, 1.0), failed as well
Error Message
Using udf_slope fails due to:
Can't initialize function 'slope'; slope() requires a real as parameter 2
Code
SELECT
D.AMOUNT,
Y.YEAR,
slope(D.AMOUNT, Y.YEAR + 0.0) as SLOPE,
intercept(D.AMOUNT, Y.YEAR + 0.0) as INTERCEPT
FROM
YEAR_REF Y,
DAILY D
Here, D.AMOUNT is a FLOAT and Y.YEAR is an INTEGER.
Create Function
The slope function was created as follows:
CREATE AGGREGATE FUNCTION slope
RETURNS REAL SONAME 'udf_slope.so';
Function Signature
From udf_slope.cc:
double slope( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char* is_error )
Example Usages
Reading the fine manual reveals:
UDF intercept()
Calculates the intercept of the linear regression of two sets of variables.
Function name intercept
Input parameter(s) 2 (dependent variable: REAL, independent variable: REAL)
Examples SELECT intercept(income,age) FROM customers
UDF slope()
Calculates the slope of the linear regression of two sets of variables.
Function name slope
Input parameter(s) 2 (dependent variable: REAL, independent variable: REAL)
Examples SELECT slope(income,age) FROM customers
Thoughts?
Thank you!
