diff --git a/mats/5_3.ms b/mats/5_3.ms
index d235d0c387..fc84f82118 100644
--- a/mats/5_3.ms
+++ b/mats/5_3.ms
@@ -1694,6 +1694,7 @@
     (eqv? (/ 1 -1/2) -2)
     (fl~= (/ 1.0 2) 0.5)
     (fl~= (/ 1 2.0) 0.5)
+    (eqv? (/ 0 2.0) 0)
     (eqv? (/ 3/5 2/5) 3/2)
     (eqv? (/ -3/5 2/5) -3/2)
     (eqv? (/ 3/5 -2/5) -3/2)
@@ -1706,11 +1707,13 @@
     (eqv? (/ 2 3 4) 1/6)
     (eqv? (/ 2 3 4 5) 1/30)
     (eqv? (/ 2/3 3/4 4/5 5/6) 4/3)
+    (eqv? (/ 0 2/3) 0)
     (cfl~= (/ -5.0+10.0i 1.0+2.0i) 3.0+4.0i)
     (cfl~= (/ -6.0-8.0i -2.0) 3.0+4.0i)
     (cfl~= (/ 26.0 3.0-2.0i) 6.0+4.0i)
     (cfl~= (/ -8.0+6.0i +2.0i) 3.0+4.0i)
     (cfl~= (/ +26.0i 3.0+2.0i) 4.0+6.0i)
+    (eqv? (/ 0 3.0+2.0i) 0)
     (let ([v '#(100 32.23 22/33 44-79i 2.9+8.7i)])
        (let f ([i 0])
           (or (= i (vector-length v))
@@ -1730,9 +1733,20 @@
     (let ([x (/ 9 50000000000)])
       (and (eqv? (numerator x) 9)
            (eqv? (denominator x) 50000000000)))
-    (== (/ 3.5 0) +inf.0)
-    (== (/ -3.5 0) -inf.0)
-    (== (/ 0.0 0) (nan))
+    (error? (/ 3.5 0))
+    (error? (/ -3.5 0))
+    (error? (/ 0.0 0))
+    (eqv? (/ 3.5 0.0) +inf.0)
+    (eqv? (/ -3.5 0.0) -inf.0)
+    (== (/ 0.0 0.0) +nan.0)
+    (eqv? (/ 0 0.0) 0)
+    (eqv? (/ 0 +inf.0) 0)
+    (eqv? (/ 0 -inf.0) 0)
+    (eqv? (/ 0 +nan.0) 0)
+    (eqv? (/ 0 2+3i) 0)
+    (eqv? (/ 0 2/3) 0)
+    (eqv? (/ 0 2.0+3.0i) 0)
+    (eqv? (/ 0 +nan.0+nan.0i) 0)
     (test-cp0-expansion eqv? '(/ 1 2) 1/2)
     (test-cp0-expansion eqv? '(/ 1 -2) -1/2)
     (test-cp0-expansion eqv? '(/ 1/2 -2) -1/4)
@@ -1756,9 +1770,9 @@
     (test-cp0-expansion cfl~= '(/ 26.0 3.0-2.0i) 6.0+4.0i)
     (test-cp0-expansion cfl~= '(/ -8.0+6.0i +2.0i) 3.0+4.0i)
     (test-cp0-expansion cfl~= '(/ +26.0i 3.0+2.0i) 4.0+6.0i)
-    (test-cp0-expansion == '(/ 3.5 0) +inf.0)
-    (test-cp0-expansion == '(/ -3.5 0) -inf.0)
-    (test-cp0-expansion == '(/ 0.0 0) (nan))
+    (test-cp0-expansion == '(/ 3.5 0.0) +inf.0)
+    (test-cp0-expansion == '(/ -3.5 0.0) -inf.0)
+    (test-cp0-expansion == '(/ 0.0 0.0) (nan))
  )
 
 (mat nan?
@@ -2146,6 +2160,8 @@
     (fl= (round 2.5) 2.0)
     (fl= (round 0.5000000000000000) 0.0)
     (fl= (round 0.5000000000000001) 1.0)
+    (eqv? (round 0.0) 0.0)
+    (eqv? (round -0.0) -0.0)
  )
 
 (mat abs
@@ -2354,11 +2370,42 @@
     (eqv? (expt 10.0 -20) 1e-20)
     (eqv? (expt 2 10) 1024)
     (eqv? (expt 0 0) 1)
+    (eqv? (expt 1.0 0) 1)
+    (eqv? (expt +nan.0 0) 1)
+    (eqv? (expt +inf.0 0) 1)
+    (eqv? (expt -inf.0 0) 1)
+    (eqv? (expt 2+3i 0) 1)
+    (eqv? (expt 2.0+3.0i 0) 1)
+    (eqv? (expt 2/3 0) 1)
+    (eqv? (expt 1 2) 1)
+    (eqv? (expt 1 2.0) 1)
+    (eqv? (expt 1 +inf.0) 1)
+    (eqv? (expt 1 -inf.0) 1)
+    (eqv? (expt 1 +nan.0) 1)
+    (eqv? (expt 1 2+3i) 1)
+    (eqv? (expt 1 2.0+3.0i) 1)
+    (eqv? (expt 1 -2.0+3.0i) 1)
+    (eqv? (expt 1 2/3) 1)
+    (eqv? (expt 1 -2/3) 1)
     (eqv? (expt 0 2) 0)
+    (eqv? (expt 0 2.0) 0)
+    (== (expt 0 +nan.0) +nan.0)
+    (eqv? (expt 0 +inf.0) 0)
+    (eqv? (expt 0 2.0+3.0i) 0)
+    (error? (expt 0 -1))
+    (error? (expt 0 -1.0))
+    (error? (expt 0 -2.0+3.0i))
+    (error? (expt 0 0.0+3.0i))
+    (error? (expt 0 -0.0+3.0i))
+    (error? (expt 0 +nan.0+3.0i))
+    (error? (expt 0 0+3i))
+    (error? (expt 0 -1/2))
+    (eqv? (expt 0 0.0) 1.0)
+    (eqv? (expt 0 -0.0) 1.0)
     (eqv? (expt 100 0) 1)
     (eqv? (expt 2 -10) 1/1024)
     (eqv? (expt -1/2 5) -1/32)
-    (fl~= (expt 9 1/2) 3.0)
+    (eqv? (expt 9 1/2) 3)
     (fl~= (expt 3.0 3) 27.0)
     (~= (expt -0.5 2) .25)
     (~= (expt -0.5 -2) 4.0)
@@ -2366,10 +2413,31 @@
     (fl= (expt 0.0 2.0) 0.0)
     (fl= (expt 0.0 0.0) 1.0)
     (fl= (expt 2.0 0.0) 1.0)
+    (eqv? (expt 1 0.0) 1)
+    (fl= (expt -1 0.0) 1.0)
+    (fl= (expt -1.0 0.0) 1.0)
+    (fl= (expt 2/3 0.0) 1.0)
+    (fl= (expt -2/3 0.0) 1.0)
+    (fl= (expt +inf.0 0.0) 1.0)
+    (fl= (expt -inf.0 0.0) 1.0)
+    (fl= (expt +nan.0 0.0) 1.0)
+    (fl= (expt 1.0 1) 1.0)
+    (fl= (expt 1.0 -1) 1.0)
+    (fl= (expt 1.0 3.0) 1.0)
+    (fl= (expt 1.0 -3.0) 1.0)
+    (fl= (expt 1.0 +inf.0) 1.0)
+    (fl= (expt 1.0 -inf.0) 1.0)
+    (fl= (expt 1.0 +nan.0) 1.0)
+    (eqv? (expt 0.0 3) 0.0)
+    (eqv? (expt 0.0 3.0) 0.0)
+    (eqv? (expt 0.0 2/3) 0.0)
+    (eqv? (expt 0.0 -3) +inf.0)
+    (eqv? (expt 0.0 -3.0) +inf.0)
+    (eqv? (expt 0.0 -2/3) +inf.0)
     (eqv? (expt -2/3 -3) -27/8)
     (fl= (expt 10.0 -1000) 0.0)
     (fl= (expt .1 1000) 0.0)
-    (cfl~= (expt -1 1/2) +1.0i)
+    (eqv? (expt -1 1/2) +1i)
     (cfl~= (expt 2.4-.3i 3.0) (* 2.4-.3i 2.4-.3i 2.4-.3i))
     (cfl~= (expt 2.4-.3i 3) (* 2.4-.3i 2.4-.3i 2.4-.3i))
     (cfl~= (expt 7.7-11.11i -2.0) (* (/ 1.0 7.7-11.11i) (/ 1.0 7.7-11.11i)))
@@ -2582,6 +2650,13 @@
        (fl= (angle 3.0@2.0) 2.0))
    (let ([z 24.3-200.2i]) (cfl~= z (make-polar (magnitude z) (angle z))))
    (= (angle 3+1i) (angle 3.0+1.0i))
+   (eqv? (angle 7.0) 0)
+   (fl~= (angle -7.0) pi)
+   (eqv? (angle 7/3) 0)
+   (fl~= (angle -7/3) pi)
+   (eqv? (angle +inf.0) 0)
+   (fl~= (angle -inf.0) pi)
+   (== (angle +nan.0) +nan.0)
  )
 
 (mat sqrt
diff --git a/s/5_3.ss b/s/5_3.ss
index 97b71d9616..a57b3f06f8 100644
--- a/s/5_3.ss
+++ b/s/5_3.ss
@@ -632,7 +632,7 @@
 (define exact-inexact/
    (lambda (x y)
       (cond
-         [(fixnum? x) (fl/ (fixnum->flonum x) y)]
+         [(fixnum? x) (if (fx= x 0) 0 (fl/ (fixnum->flonum x) y))]
          [(floatable? x) (fl/ (inexact x) y)]
          [(or (fl= y 0.0) (exceptional-flonum? y))
           (if (< x 0) (fl/ -1.0 y) (fl/ y))]
@@ -641,7 +641,7 @@
 (define inexact-exact/
    (lambda (x y)
       (cond
-         [(fixnum? y) (fl/ x (fixnum->flonum y))]
+         [(fixnum? y) (if (eq? y 0) (domain-error '/ y) (fl/ x (fixnum->flonum y)))]
          [(floatable? y) (fl/ x (inexact y))]
          [(or (fl= x 0.0) (exceptional-flonum? x)) (if (< y 0) (fl- x) x)]
          [else (inexact (/ (exact x) y))])))
@@ -1266,7 +1266,10 @@
 (set! angle
    (lambda (z)
       (type-case z
-         [(flonum?) (if (negated-flonum? z) pi 0.0)]
+         [(flonum?) (cond
+                     [($nan? z) +nan.0]
+                     [(negated-flonum? z) pi]
+                     [else 0])]
          [($inexactnum?) (cflangle z)]
          [(fixnum? bignum? ratnum?)
           (cond
@@ -1475,28 +1478,47 @@
          [(flonum?)
           (type-case x
              [(flonum?)
-              (if (and (fl< x 0.0) (not ($flinteger-or-inf? y)))
+              (if (and (fl< x 0.0) (not ($flinteger? y)))
                   (exp (* y (log x)))
                   ($flexpt x y))]
              [($inexactnum? $exactnum?) (exp (* y (log x)))]
              [(fixnum? bignum? ratnum?)
-              (if (floatable? x)
-                  (expt (inexact x) y)
-                  (exp (* y (log x))))]
+              (cond
+               [(eq? x 0)
+                (cond
+                 [(fl< y 0.0) ($impoops 'expt "undefined for values ~s and ~s" x y)]
+                 [(fl= y 0.0) 1.0]
+                 [($nan? y) +nan.0]
+                 [else 0])]
+               [(eq? x 1) 1]
+               [else
+                (if (floatable? x)
+                    (expt (inexact x) y)
+                    (exp (* y (log x))))])]
              [else (nonnumber-error 'expt x)])]
          [($inexactnum?)
-          (if (or (eq? x 0) (and (flonum? x) (= x 0.0)))
-              0.0 
-              (begin
-                (unless (number? x) (nonnumber-error 'expt x))
-                (exp (* y (log x)))))]
+          (cond
+           [(eq? x 0)
+            (let ([r ($inexactnum-real-part y)])
+              (cond
+               [(fl> r 0.0) 0]
+               [else
+                ($impoops 'expt "undefined for values ~s and ~s" x y)]))]
+           [(eq? x 1) 1]
+           [(and (flonum? x) (fl= x 0.0) (not (negated-flonum? ($inexactnum-real-part y))))
+            0.0]
+           [else
+            (unless (number? x) (nonnumber-error 'expt x))
+            (exp (* y (log x)))])]
          [(ratnum? $exactnum?)
           (unless (number? x) (nonnumber-error 'expt x))
           (cond
+             [(eqv? y 1/2) (sqrt x)]
              [(eq? x 0)
               (if (> (real-part y) 0)
                   0
                   ($impoops 'expt "undefined for values ~s and ~s" x y))]
+             [(eq? x 1) 1]
              [(floatable? y) (expt x (inexact y))]
              [else (exp (* y (log x)))])]
          [else (nonnumber-error 'expt y)])))
@@ -2215,9 +2237,11 @@
           (type-case x
              [(fixnum? bignum? ratnum? flonum?)
               ;; a / c+di => c(a/(cc+dd)) + (-d(a/cc+dd))i
-              (let ([c (real-part y)] [d (imag-part y)])
-                 (let ([t (/ x (+ (* c c) (* d d)))])
-                    (make-rectangular (* c t) (- (* d t)))))]
+              (if (eq? x 0)
+                  0
+                  (let ([c (real-part y)] [d (imag-part y)])
+                    (let ([t (/ x (+ (* c c) (* d d)))])
+                      (make-rectangular (* c t) (- (* d t))))))]
              [($exactnum? $inexactnum?)
               ;; a+bi / c+di => (ac+bd)/(cc+dd) + ((bc-ad)/(cc+dd))i
               (let ([a (real-part x)] [b (imag-part x)]
diff --git a/s/cp0.ss b/s/cp0.ss
index 2fa2c74db2..e9f0e38ff3 100644
--- a/s/cp0.ss
+++ b/s/cp0.ss
@@ -2699,7 +2699,7 @@
                        [else #f])])
            (and xval
                 yval
-                (or (not (eq? xval 0)) (not (fixnum? yval)) (fx>= yval 0))
+                (not (and (eq? xval 0) (negative? (real-part yval))))
                 (begin
                   (residualize-seq '() (list x y) ctxt)
                   `(quote ,(expt xval yval)))))])
diff --git a/s/library.ss b/s/library.ss
index c7476b8c0f..9de734acba 100644
--- a/s/library.ss
+++ b/s/library.ss
@@ -624,13 +624,15 @@
     [(ieee)
      (define threshold+ #i#x10000000000000)
      (define threshold- #i#x-10000000000000)])
-  (if (fl>= x 0.0)
-      (if (fl< x threshold+)
-          (fl- (fl+ x threshold+) threshold+)
-          x)
-      (if (fl> x threshold-)
-          (fl- (fl+ x threshold-) threshold-)
-          x)))
+  (if (fl= x 0.0)
+      x ; don't change sign
+      (if (fl>= x 0.0)
+          (if (fl< x threshold+)
+              (fl- (fl+ x threshold+) threshold+)
+              x)
+          (if (fl> x threshold-)
+              (fl- (fl+ x threshold-) threshold-)
+              x))))
 
 ;;; The generic comparison entries assume the fixnum case is inlined.