deal with zero: "Error: CVodeMalloc/CVRelnit y0=NULL illegal"

Question

Hi! I want to calculate a variable Y = X1/X2. Since X2 can become 0, I use a "merge" block to prevent the denominator to be zero (i.e., when X2 < 1e-8). When I used "Euler" integration method, the program ran successfully. However, when I changed the method to "Adaptive BDF", an error occured "CVodeMalloc/CVReInit-- y0=NULL illegal".

Can I fix this error and still use "Adaptive BDF" method? (because in my case the Adaptive BDF is the fastest method)

Below I attached the example program.

Example.zip

pdarnell · Accepted Answer

Hi Tom,

That inscrutable error message is really just saying that in order to perform integration you need at least one integrator, but you don't have any integrators in your diagram. As long as you use at least one integrator you will be fine with the Adaptive BDF integration method.

We will quietly ignore use of Adaptive BDF with 0 integrators in the next release.

Regards,

Pete