[Gretl-devel] argument type problem when 1x1 matrix is coerced to scalar
Sven Schreiber
svetosch at gmx.net
Thu Jul 16 12:10:21 EDT 2015
Hi,
while I was testing the SVAR addon I ran into a bug that has its roots
in gretl. The code below shows the problem, namely that even though the
function hey() officially returns a matrix, if it's a 1x1 matrix _and_
if the caller does not explicitly cast the output to a matrix type (with
the 'matrix' alias for genr), then gretl puts the return value into a
scalar type. And if the caller then wants to use this variable as a
matrix (because that's what it's supposed to be), it fails.
So I think gretl should honor the return type of a user-defined function
always. I know that sometimes gretl has to convert a 1x1 matrix to a
scalar, for example if vec(a)'vec(a) is treated by the programmer as a
number for further stuff. But somehow gretl does it prematurely here.
thanks,
sven
<hansl>
function void hu(matrix *m)
print "ouf"
end function
function matrix hey(bool in)
if in
return zeros(2,2)
else
return zeros(1,1)
endif
end function
out2 = hey(1)
hu(&out2) # works
matrix out3 = hey(0)
hu(&out3) # works
out = hey(0)
hu(&out) # fails, wrong argument type
</hansl>
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