excel - Optional Array in vb.net xll custom function -

excel - Optional Array in vb.net xll custom function -

i converting vba code vb.net .xll visual studio , having problem next function,

public shared function whitenwithbypasscurve(byval rngep() double, _ byval rngrho50() double, _ byval rngt0() double, _ byval rngt1() double, _ byval rngsgs() double, _ optional byval argmediumsplitlimitsize double = nothing, _ optional byval rngsizes() double = nothing, _ optional byval argmediumsplit double = nil _ ) object

now function work fine long have range in rngsizes() term not step function if term not included. help appreciated

vb.net excel