From 2b5831d68df1824881f9117bf2297957a6e49f64 Mon Sep 17 00:00:00 2001
From: John Darrington <john@darrington.wattle.id.au>
Date: Sat, 31 Jul 2010 11:55:18 +0200
Subject: [PATCH] FACTOR: prevent crash if the dataset is empty.

The FACTOR command crashed if there were no cases
which had non-missing values for all variables.
This change emits a warning in this case and does
no analysis.
---
 src/language/stats/factor.c    |  6 ++++++
 src/math/covariance.c          |  6 ++++--
 tests/language/stats/factor.at | 22 +++++++++++++++++++++-
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/language/stats/factor.c b/src/language/stats/factor.c
index a2a8e5df03..d50d6ad3fd 100644
--- a/src/language/stats/factor.c
+++ b/src/language/stats/factor.c
@@ -1694,6 +1694,12 @@ do_factor (const struct cmd_factor *factor, struct casereader *r)
 
   idata->cov = covariance_calculate (cov);
 
+  if (idata->cov == NULL)
+    {
+      msg (MW, _("The dataset contains no complete observations. No analysis will be performed."));
+      goto finish;
+    }
+
   var_matrix = covariance_moments (cov, MOMENT_VARIANCE);
   mean_matrix = covariance_moments (cov, MOMENT_MEAN);
   idata->n = covariance_moments (cov, MOMENT_NONE);
diff --git a/src/math/covariance.c b/src/math/covariance.c
index 61f54f5075..b5a4166dfa 100644
--- a/src/math/covariance.c
+++ b/src/math/covariance.c
@@ -601,7 +601,8 @@ covariance_calculate_single_pass (struct covariance *cov)
 const gsl_matrix *
 covariance_calculate (struct covariance *cov)
 {
-  assert ( cov->state > 0 );
+  if ( cov->state <= 0 )
+    return NULL;
 
   switch (cov->passes)
     {
@@ -681,7 +682,8 @@ covariance_calculate_single_pass_unnormalized (struct covariance *cov)
 const gsl_matrix *
 covariance_calculate_unnormalized (struct covariance *cov)
 {
-  assert ( cov->state > 0 );
+  if ( cov->state <= 0 )
+    return NULL;
 
   switch (cov->passes)
     {
diff --git a/tests/language/stats/factor.at b/tests/language/stats/factor.at
index f1d4b2360b..ca01ca8051 100644
--- a/tests/language/stats/factor.at
+++ b/tests/language/stats/factor.at
@@ -1775,4 +1775,24 @@ science,.900,.198
 socst,.222,.922
 ])
 
-AT_CLEANUP
\ No newline at end of file
+AT_CLEANUP
+
+
+
+AT_SETUP([FACTOR empty dataset])
+dnl Test that something sane happens when the dataset contains no complete observations
+
+AT_DATA([factor-empty.sps],
+  [data list notable list /x * y * z *.
+begin data.
+3.4        .     92.9
+.        32.09   34.2
+1.00     19.80     .
+2.00       .      3.6
+end data.
+
+factor /variables = ALL.
+])
+
+AT_CHECK([pspp -O format=csv factor-empty.sps], [0], [ignore])
+AT_CLEANUP
-- 
2.30.2