diff --git a/examples/GLIsosurface.py b/examples/GLIsosurface.py
index 16045a78..3da8dfa5 100644
--- a/examples/GLIsosurface.py
+++ b/examples/GLIsosurface.py
@@ -7,6 +7,7 @@ This example uses the isosurface function to convert a scalar field
 ## Add path to library (just for examples; you do not need this)
 import initExample
 
+import numpy as np
 from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph as pg
 import pyqtgraph.opengl as gl
@@ -22,23 +23,17 @@ g = gl.GLGridItem()
 g.scale(2,2,1)
 w.addItem(g)
 
-import numpy as np
-
 ## Define a scalar field from which we will generate an isosurface
 def psi(i, j, k, offset=(25, 25, 50)):
     x = i-offset[0]
     y = j-offset[1]
     z = k-offset[2]
-    th = np.arctan2(z, (x**2+y**2)**0.5)
+    th = np.arctan2(z, np.sqrt(x**2+y**2))
     phi = np.arctan2(y, x)
-    r = (x**2 + y**2 + z **2)**0.5
+    r = np.sqrt(x**2 + y**2 + z **2)
     a0 = 1
-    #ps = (1./81.) * (2./np.pi)**0.5 * (1./a0)**(3/2) * (6 - r/a0) * (r/a0) * np.exp(-r/(3*a0)) * np.cos(th)
     ps = (1./81.) * 1./(6.*np.pi)**0.5 * (1./a0)**(3/2) * (r/a0)**2 * np.exp(-r/(3*a0)) * (3 * np.cos(th)**2 - 1)
-    
     return ps
-    
-    #return ((1./81.) * (1./np.pi)**0.5 * (1./a0)**(3/2) * (r/a0)**2 * (r/a0) * np.exp(-r/(3*a0)) * np.sin(th) * np.cos(th) * np.exp(2 * 1j * phi))**2 
 
 
 print("Generating scalar field..")
diff --git a/examples/GLVolumeItem.py b/examples/GLVolumeItem.py
index 5d7e6601..601ddfa1 100644
--- a/examples/GLVolumeItem.py
+++ b/examples/GLVolumeItem.py
@@ -7,6 +7,7 @@ Demonstrates GLVolumeItem for displaying volumetric data.
 ## Add path to library (just for examples; you do not need this)
 import initExample
 
+import numpy as np
 import pyqtgraph as pg
 from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph.opengl as gl
@@ -23,7 +24,6 @@ g = gl.GLGridItem()
 g.scale(10, 10, 1)
 w.addItem(g)
 
-import numpy as np
 ## Hydrogen electron probability density
 def psi(i, j, k, offset=(50,50,100)):
     x = i-offset[0]
diff --git a/examples/GLshaders.py b/examples/GLshaders.py
index 4e1acc51..38e6988d 100644
--- a/examples/GLshaders.py
+++ b/examples/GLshaders.py
@@ -9,6 +9,7 @@ used to affect the appearance of a surface.
 ## Add path to library (just for examples; you do not need this)
 import initExample
 
+import numpy as np
 from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph as pg
 import pyqtgraph.opengl as gl
@@ -23,9 +24,6 @@ g = gl.GLGridItem()
 g.scale(2,2,1)
 w.addItem(g)
 
-import numpy as np
-
-
 md = gl.MeshData.sphere(rows=10, cols=20)
 x = np.linspace(-8, 8, 6)
 
diff --git a/examples/optics/pyoptic.py b/examples/optics/pyoptic.py
index f70edd2a..811ae665 100644
--- a/examples/optics/pyoptic.py
+++ b/examples/optics/pyoptic.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+from math import atan2, asin, sin, cos, sqrt, pi
 import pyqtgraph as pg
 from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
@@ -49,7 +50,7 @@ class GlassDB:
             B = list(map(float, [info['B1'], info['B2'], info['B3']]))
             C = list(map(float, [info['C1'], info['C2'], info['C3']]))
             w2 = (wl/1000.)**2
-            n = np.sqrt(1.0 + (B[0]*w2 / (w2-C[0])) + (B[1]*w2 / (w2-C[1])) + (B[2]*w2 / (w2-C[2])))
+            n = sqrt(1.0 + (B[0]*w2 / (w2-C[0])) + (B[1]*w2 / (w2-C[1])) + (B[2]*w2 / (w2-C[2])))
             cache[wl] = n
         return cache[wl]
         
@@ -249,10 +250,14 @@ class Lens(Optic):
             p1 = surface.mapToItem(ray, p1)
             
             rd = ray['dir']
-            a1 = np.arctan2(rd[1], rd[0])
-            ar = a1 - ai + np.arcsin((np.sin(ai) * ray['ior'] / ior))
+
+            a1 = atan2(rd[1], rd[0])
+            try:
+                ar = a1 - ai + asin((sin(ai) * ray['ior'] / ior))
+            except ValueError:
+                ar = np.nan
             ray.setEnd(p1)
-            dp = Point(np.cos(ar), np.sin(ar))
+            dp = Point(cos(ar), sin(ar))
             ray = Ray(parent=ray, ior=ior, dir=dp)
         return [ray]
         
@@ -279,10 +284,10 @@ class Mirror(Optic):
         if p1 is not None:
             p1 = surface.mapToItem(ray, p1)
             rd = ray['dir']
-            a1 = np.arctan2(rd[1], rd[0])
-            ar = a1  + np.pi - 2*ai
+            a1 = atan2(rd[1], rd[0])
+            ar = a1  + pi - 2*ai
             ray.setEnd(p1)
-            dp = Point(np.cos(ar), np.sin(ar))
+            dp = Point(cos(ar), sin(ar))
             ray = Ray(parent=ray, dir=dp)
         else:
             ray.setEnd(None)
@@ -374,7 +379,7 @@ class CircleSurface(pg.GraphicsObject):
             ## half-height of surface can't be larger than radius
             h2 = min(h2, abs(r))
             arc = QtCore.QRectF(0, -r, r*2, r*2)
-            a1 = np.arcsin(h2/r) * 180. / np.pi
+            a1 = asin(h2/r) * 180. / pi
             a2 = -2*a1
             a1 += 180.
             self.path.arcMoveTo(arc, a1)
@@ -406,7 +411,7 @@ class CircleSurface(pg.GraphicsObject):
             if abs(y) > h:
                 return None, None
             else:
-                return (Point(0, y), np.arctan2(dir[1], dir[0]))
+                return (Point(0, y), atan2(dir[1], dir[0]))
         else:
             #print "  curve"
             ## find intersection of circle and line (quadratic formula)
@@ -436,19 +441,12 @@ class CircleSurface(pg.GraphicsObject):
                 pt = Point(x2, y2)
                 if not br.contains(x2+r, y2):
                     return None, None
-                    raise Exception("No intersection!")
                 
-            norm = np.arctan2(pt[1], pt[0])
+            norm = atan2(pt[1], pt[0])
             if r < 0:
-                norm += np.pi
-            #print "  norm:", norm*180/3.1415
+                norm += pi
             dp = p - pt
-            #print "  dp:", dp
-            ang = np.arctan2(dp[1], dp[0]) 
-            #print "  ang:", ang*180/3.1415
-            #print "  ai:", (ang-norm)*180/3.1415
-            
-            #print "  intersection:", pt
+            ang = atan2(dp[1], dp[0]) 
             return pt + Point(r, 0), ang-norm
 
             
diff --git a/pyqtgraph/Point.py b/pyqtgraph/Point.py
index fea37dda..148178f9 100644
--- a/pyqtgraph/Point.py
+++ b/pyqtgraph/Point.py
@@ -6,7 +6,7 @@ Distributed under MIT/X11 license. See license.txt for more information.
 """
 
 from .Qt import QtCore
-import numpy as np
+from math import sin, acos, atan2, inf, pi
 
 def clip(x, mn, mx):
     if x > mx:
@@ -109,9 +109,9 @@ class Point(QtCore.QPointF):
             return (self[0]**2 + self[1]**2) ** 0.5
         except OverflowError:
             try:
-                return self[1] / np.sin(np.arctan2(self[1], self[0]))
+                return self[1] / sin(atan2(self[1], self[0]))
             except OverflowError:
-                return np.inf
+                return inf
     
     def norm(self):
         """Returns a vector in the same direction with unit length."""
@@ -124,11 +124,11 @@ class Point(QtCore.QPointF):
         if n1 == 0. or n2 == 0.:
             return None
         ## Probably this should be done with arctan2 instead..
-        ang = np.arccos(clip(self.dot(a) / (n1 * n2), -1.0, 1.0)) ### in radians
+        ang = acos(clip(self.dot(a) / (n1 * n2), -1.0, 1.0)) ### in radians
         c = self.cross(a)
         if c > 0:
             ang *= -1.
-        return ang * 180. / np.pi
+        return ang * 180. / pi
     
     def dot(self, a):
         """Returns the dot product of a and this Point."""
diff --git a/pyqtgraph/SRTTransform.py b/pyqtgraph/SRTTransform.py
index 35ec0625..81bfb24d 100644
--- a/pyqtgraph/SRTTransform.py
+++ b/pyqtgraph/SRTTransform.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+from math import atan2, pi
 from .Qt import QtCore, QtGui
 from .Point import Point
 import numpy as np
@@ -76,7 +77,7 @@ class SRTTransform(QtGui.QTransform):
         self._state = {
             'pos': Point(p1),
             'scale': Point(dp2.length(), dp3.length() * sy),
-            'angle': (np.arctan2(dp2[1], dp2[0]) * 180. / np.pi) + da
+            'angle': (atan2(dp2[1], dp2[0]) * 180. / pi) + da
         }
         self.update()
         
diff --git a/pyqtgraph/SRTTransform3D.py b/pyqtgraph/SRTTransform3D.py
index 7d458edd..438a410c 100644
--- a/pyqtgraph/SRTTransform3D.py
+++ b/pyqtgraph/SRTTransform3D.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+from math import atan2, pi
 from .Qt import QtCore, QtGui
 from .Vector import Vector
 from .Transform3D import Transform3D
@@ -164,7 +165,7 @@ class SRTTransform3D(Transform3D):
         sin = (r-r.T)[rInd] / (2. * sign * axis[axisInd])
         
         ## finally, we get the complete angle from arctan(sin/cos)
-        self._state['angle'] = np.arctan2(sin, cos) * 180 / np.pi
+        self._state['angle'] = atan2(sin, cos) * 180 / pi
         if self._state['angle'] == 0:
             self._state['axis'] = (0,0,1)
         
diff --git a/pyqtgraph/graphicsItems/CurvePoint.py b/pyqtgraph/graphicsItems/CurvePoint.py
index 368a0a82..9e4d3718 100644
--- a/pyqtgraph/graphicsItems/CurvePoint.py
+++ b/pyqtgraph/graphicsItems/CurvePoint.py
@@ -1,5 +1,7 @@
+from math import atan2, pi
 from ..Qt import QtGui, QtCore
 from . import ArrowItem
+from ..functions import clip_scalar
 import numpy as np
 from ..Point import Point
 import weakref
@@ -65,22 +67,22 @@ class CurvePoint(GraphicsObject):
             
         if index != int(index):  ## interpolate floating-point values
             i1 = int(index)
-            i2 = np.clip(i1+1, 0, len(x)-1)
+            i2 = clip_scalar(i1+1, 0, len(x)-1)
             s2 = index-i1
             s1 = 1.0-s2
             newPos = (x[i1]*s1+x[i2]*s2, y[i1]*s1+y[i2]*s2)
         else:
             index = int(index)
-            i1 = np.clip(index-1, 0, len(x)-1)
-            i2 = np.clip(index+1, 0, len(x)-1)
+            i1 = clip_scalar(index-1, 0, len(x)-1)
+            i2 = clip_scalar(index+1, 0, len(x)-1)
             newPos = (x[index], y[index])
             
         p1 = self.parentItem().mapToScene(QtCore.QPointF(x[i1], y[i1]))
         p2 = self.parentItem().mapToScene(QtCore.QPointF(x[i2], y[i2]))
-        ang = np.arctan2(p2.y()-p1.y(), p2.x()-p1.x()) ## returns radians
+        ang = atan2(p2.y()-p1.y(), p2.x()-p1.x()) ## returns radians
         self.resetTransform()
         if self._rotate:
-            self.setRotation(180 + np.rad2deg(ang)) ## takes degrees
+            self.setRotation(180 + ang * (180. / pi))
         QtGui.QGraphicsItem.setPos(self, *newPos)
         return True
         
diff --git a/pyqtgraph/graphicsItems/InfiniteLine.py b/pyqtgraph/graphicsItems/InfiniteLine.py
index 74a8da95..ce96d00b 100644
--- a/pyqtgraph/graphicsItems/InfiniteLine.py
+++ b/pyqtgraph/graphicsItems/InfiniteLine.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+from math import atan2, pi
 from ..Qt import QtGui, QtCore
 from ..Point import Point
 from .GraphicsObject import GraphicsObject
@@ -359,7 +360,7 @@ class InfiniteLine(GraphicsObject):
         up = tr.map(Point(left, 1))
         dif = end - start
         length = Point(dif).length()
-        angle = np.arctan2(dif.y(), dif.x()) * 180 / np.pi
+        angle = atan2(dif.y(), dif.x()) * 180 / pi
         
         p.translate(start)
         p.rotate(angle)
diff --git a/pyqtgraph/graphicsItems/ROI.py b/pyqtgraph/graphicsItems/ROI.py
index c2cb49ed..566651b8 100644
--- a/pyqtgraph/graphicsItems/ROI.py
+++ b/pyqtgraph/graphicsItems/ROI.py
@@ -17,7 +17,7 @@ import numpy as np
 #from numpy.linalg import norm
 from ..Point import *
 from ..SRTTransform import SRTTransform
-from math import cos, sin
+from math import atan2, cos, sin, pi, sqrt
 from .. import functions as fn
 from .GraphicsObject import GraphicsObject
 from .UIGraphicsItem import UIGraphicsItem
@@ -1247,8 +1247,8 @@ class ROI(GraphicsObject):
         vx = img.mapToData(self.mapToItem(img, QtCore.QPointF(1, 0))) - origin
         vy = img.mapToData(self.mapToItem(img, QtCore.QPointF(0, 1))) - origin
         
-        lvx = np.sqrt(vx.x()**2 + vx.y()**2)
-        lvy = np.sqrt(vy.x()**2 + vy.y()**2)
+        lvx = sqrt(vx.x()**2 + vx.y()**2)
+        lvy = sqrt(vy.x()**2 + vy.y()**2)
         ##img.width is number of pixels, not width of item.
         ##need pxWidth and pxHeight instead of pxLen ?
         sx = 1.0 / lvx
@@ -1332,8 +1332,8 @@ class Handle(UIGraphicsItem):
     properties of the ROI they are attached to.
     """
     types = {   ## defines number of sides, start angle for each handle type
-        't': (4, np.pi/4),
-        'f': (4, np.pi/4), 
+        't': (4, pi/4),
+        'f': (4, pi/4), 
         's': (4, 0),
         'r': (12, 0),
         'sr': (12, 0),
@@ -1481,7 +1481,7 @@ class Handle(UIGraphicsItem):
         size = self.radius
         self.path = QtGui.QPainterPath()
         ang = self.startAng
-        dt = 2*np.pi / self.sides
+        dt = 2 * pi / self.sides
         for i in range(0, self.sides+1):
             x = size * cos(ang)
             y = size * sin(ang)
@@ -1518,13 +1518,13 @@ class Handle(UIGraphicsItem):
             return None
         
         v = dt.map(QtCore.QPointF(1, 0)) - dt.map(QtCore.QPointF(0, 0))
-        va = np.arctan2(v.y(), v.x())
+        va = atan2(v.y(), v.x())
         
         dti = fn.invertQTransform(dt)
         devPos = dt.map(QtCore.QPointF(0,0))
         tr = QtGui.QTransform()
         tr.translate(devPos.x(), devPos.y())
-        tr.rotate(va * 180. / 3.1415926)
+        tr.rotate(va * 180. / pi)
         
         return dti.map(tr.map(self.path))
         
@@ -1663,7 +1663,7 @@ class LineROI(ROI):
         d = pos2-pos1
         l = d.length()
         ang = Point(1, 0).angle(d)
-        ra = ang * np.pi / 180.
+        ra = ang * pi / 180.
         c = Point(-width/2. * sin(ra), -width/2. * cos(ra))
         pos1 = pos1 + c
         
@@ -1914,7 +1914,7 @@ class EllipseROI(ROI):
             center = br.center()
             r1 = br.width() / 2.
             r2 = br.height() / 2.
-            theta = np.linspace(0, 2*np.pi, 24)
+            theta = np.linspace(0, 2 * pi, 24)
             x = center.x() + r1 * np.cos(theta)
             y = center.y() + r2 * np.sin(theta)
             path.moveTo(x[0], y[0])
@@ -2396,7 +2396,7 @@ class TriangleROI(ROI):
     def __init__(self, pos, size, **args):
         ROI.__init__(self, pos, [size, size], **args)
         self.aspectLocked = True
-        angles = np.linspace(0, np.pi * 4 / 3, 3)
+        angles = np.linspace(0, pi * 4 / 3, 3)
         verticies = (np.array((np.sin(angles), np.cos(angles))).T + 1.0) / 2.0
         self.poly = QtGui.QPolygonF()
         for pt in verticies:
diff --git a/pyqtgraph/graphicsItems/TextItem.py b/pyqtgraph/graphicsItems/TextItem.py
index 8dcb04f6..6b2dfdd5 100644
--- a/pyqtgraph/graphicsItems/TextItem.py
+++ b/pyqtgraph/graphicsItems/TextItem.py
@@ -1,4 +1,4 @@
-import numpy as np
+from math import pi, atan2
 from ..Qt import QtCore, QtGui
 from ..Point import Point
 from .. import functions as fn
@@ -208,7 +208,7 @@ class TextItem(GraphicsObject):
         angle = -self.angle
         if self.rotateAxis is not None:
             d = pt.map(self.rotateAxis) - pt.map(Point(0, 0))
-            a = np.arctan2(d.y(), d.x()) * 180 / np.pi
+            a = atan2(d.y(), d.x()) * 180 / pi
             angle += a
         t.rotate(angle)  
         self.setTransform(t)