R help - Apr 2019 - Difference between cor_auto (qgraph package) and lavCor (lavaan package)

Hello,
I would like to know the diffrence between 2 commands : cor_auto (from qgraph
package) and lavCor (from lavaan package) to compute a polychoric correlation
matrix in order to do a network analysis.
I have the responses to the SF-36 questionnaire (36 items with ordered
responses) and I would like to have a polychoric correlation matrix by following
the Sacha Epskamp's method.?But I have a warning if using cor_auto
:??"Correlation matrix is not positive definite. Finding nearest positive
definite matrix". I can ignore this warning or not ? Because I try to do a
polychoric matrix in STATA software and I do not have a warning message.
And I don't understand the difference between lavCor command, because When I
use lavCor, I do not have the warning message either.
//cor.auto1 <- cor_auto(Data_1it)
//cor.lav1<-lavCor(Data_1it, ordered=names(Data_1it))
Thank you in advance for your answer.?
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