3 files changed, 35 insertions, 8 deletions
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index e59d6ee78e..879600b9b1 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -47,6 +47,7 @@
 #include "nvim/indent_c.h"
 #include "nvim/indent.h"
 #include "nvim/mark.h"
+#include "nvim/math.h"
 #include "nvim/mbyte.h"
 #include "nvim/memline.h"
 #include "nvim/memory.h"
@@ -11289,7 +11290,6 @@ static void f_has(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 #endif
     "tablineat",
     "tag_binary",
-    "tag_old_static",
     "termguicolors",
     "termresponse",
     "textobjects",
@@ -12042,6 +12042,21 @@ static void f_islocked(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   clear_lval(&lv);
 }
 
+// "isinf()" function
+static void f_isinf(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  if (argvars[0].v_type == VAR_FLOAT
+      && xisinf(argvars[0].vval.v_float)) {
+    rettv->vval.v_number = argvars[0].vval.v_float > 0.0 ? 1 : -1;
+  }
+}
+
+// "isnan()" function
+static void f_isnan(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  rettv->vval.v_number = argvars[0].v_type == VAR_FLOAT
+    && xisnan(argvars[0].vval.v_float);
+}
 
 /// Turn a dictionary into a list
 ///
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index c87fb534c6..ebdf3f5489 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -189,7 +189,9 @@ return {
     insert={args={2, 3}},
     invert={args=1},
     isdirectory={args=1},
+    isinf={args=1},
     islocked={args=1},
+    isnan={args=1},
     id={args=1},
     items={args=1},
     jobclose={args={1, 2}, func="f_chanclose"},
diff --git a/src/nvim/testdir/test_float_func.vim b/src/nvim/testdir/test_float_func.vim
index 5ea5192994..154ef570e0 100644
--- a/src/nvim/testdir/test_float_func.vim
+++ b/src/nvim/testdir/test_float_func.vim
@@ -288,14 +288,24 @@ func Test_trunc()
   call assert_fails("call trunc('')", 'E808:')
 endfunc
 
+func Test_isinf()
+  call assert_equal(1, isinf(1.0/0.0))
+  call assert_equal(-1, isinf(-1.0/0.0))
+  call assert_false(isinf(1.0))
+  call assert_false(isinf(0.0/0.0))
+  call assert_false(isinf('a'))
+  call assert_false(isinf([]))
+  call assert_false(isinf({}))
+endfunc
+
 func Test_isnan()
-  throw 'skipped: Nvim does not support isnan()'
-  call assert_equal(0, isnan(1.0))
-  call assert_equal(1, isnan(0.0/0.0))
-  call assert_equal(0, isnan(1.0/0.0))
-  call assert_equal(0, isnan('a'))
-  call assert_equal(0, isnan([]))
-  call assert_equal(0, isnan({}))
+  call assert_true(isnan(0.0/0.0))
+  call assert_false(isnan(1.0))
+  call assert_false(isnan(1.0/0.0))
+  call assert_false(isnan(-1.0/0.0))
+  call assert_false(isnan('a'))
+  call assert_false(isnan([]))
+  call assert_false(isnan({}))
 endfunc
 
 " This was converted from test65