How to specify coefficients of variable terms in ODE system

Hi everyone,

I need to specify the coefficients of the ODE variables g and f as a predetermined variables but matlab only accepts numerical values as coefficients of its differential variables. Is there any way to fix this?

[f, g] = dsolve('D2f == A*f + B*g', 'Dg == C*f + H*g')

where A, B, C and H are predetermined terms.

Thanks in advance.