myModel <- 'x1 ~ a*x2 + b*x3 + c*x4'
myParTable <- lavaanify(myModel, as.data.frame. = FALSE)
con <- ' a == 2*b
b - c == 5 '
conInfo <- lav_constraints_parse(myParTable, constraints = con)
myModel2 <- 'x1 ~ a*x2 + b*x3 + c*x4
a == 2*b
b - c == 5 '
ceq <- lav_partable_constraints_ceq(partable = lavaanify(myModel2))
ceq( c(2,3,4) )
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