(calcFunc-apart): Improve test for rational functions.

2 files changed, 22 insertions, 15 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 01e8e2dfdf2..5550a2ceb83 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2009-01-24  Jay Belanger  <jay.p.belanger@gmail.com>
+
+        * calc/calc-poly.el (calcFunc-apart): Improve test for
+        rational functions.
+
 2009-01-23  Chong Yidong  <cyd@stupidchicken.com>
 
         * mail/rmailsum.el (rmail-summary-by-labels): Correctly handle
diff --git a/lisp/calc/calc-poly.el b/lisp/calc/calc-poly.el
index 7385e42c851..2246df94414 100644
--- a/lisp/calc/calc-poly.el
+++ b/lisp/calc/calc-poly.el
@@ -961,22 +961,24 @@
         ((eq (car expr) '-)
          (math-sub (calcFunc-apart (nth 1 expr) var)
                    (calcFunc-apart (nth 2 expr) var)))
-        ((not (math-ratpoly-p expr var))
-         (math-reject-arg expr "Expected a rational function"))
+        ((and var (not (math-ratpoly-p expr var)))
+         (math-reject-arg expr "Expected a rational function"))
         (t
-         (let* ((calc-prefer-frac t)
-                (rat (math-to-ratpoly expr))
-                (num (car rat))
-                (den (cdr rat))
-                (qr (math-poly-div num den))
-                (q (car qr))
-                (r (cdr qr)))
-           (or var
-               (setq var (math-polynomial-base den)))
-           (math-add q (or (and var
-                                (math-expr-contains den var)
-                                (math-partial-fractions r den var))
-                           (math-div r den)))))))
+         (let* ((calc-prefer-frac t)
+                (rat (math-to-ratpoly expr))
+                (num (car rat))
+                (den (cdr rat)))
+           (or var
+               (setq var (math-polynomial-base den)))
+           (if (not (math-ratpoly-p expr var))
+               (math-reject-arg expr "Expected a rational function")
+             (let* ((qr (math-poly-div num den))
+                    (q (car qr))
+                    (r (cdr qr)))
+               (math-add q (or (and var
+                                    (math-expr-contains den var)
+                                    (math-partial-fractions r den var))
+                               (math-div r den)))))))))
 
 
 (defun math-padded-polynomial (expr var deg)