In the ICPlan, compute_drift() returns (-drift, diffusion).
However, in VPCPlan, I think compute_drift() returns (drift, diffusion).
drift = d_alpha_alpha_ratio x, for VPCPlan, d_alpha_alpha_ratio= -0.5 \beta
but compute_drift() in VPCPlan returns -0.5\beta instead of 0.5\beta
In the ICPlan, compute_drift() returns (-drift, diffusion).
However, in VPCPlan, I think compute_drift() returns (drift, diffusion). drift = d_alpha_alpha_ratio x, for VPCPlan, d_alpha_alpha_ratio= -0.5 \beta but compute_drift() in VPCPlan returns -0.5\beta instead of 0.5\beta
Their signs on drift are incosistent.