diff --git a/raytracing/matrix.py b/raytracing/matrix.py
index 43f9790..c84cede 100644
--- a/raytracing/matrix.py
+++ b/raytracing/matrix.py
@@ -846,7 +846,8 @@ class Matrix(object):
 
     @property
     def hasPower(self):
-        """ If True, then there is a non-null focal length because C!=0
+        """ If True, then there is a non-null focal length because C!=0. We compare to an epsilon value, because
+        computational errors can occur and lead to C being very small, but not 0.
 
         Examples
         --------
@@ -861,7 +862,7 @@ class Matrix(object):
         >>> print('hasPower:' , M2.hasPower)
         hasPower: False
         """
-        return self.C != 0
+        return abs(self.C) > Matrix.__epsilon__
 
     def pointsOfInterest(self, z):
         """ Any points of interest for this matrix (focal points,

Matrix: hasPower returns True when it should be False
When we want to know if a `Matrix` has power, we check if `self.C != 0`. In some cases, computational errors occurs due to the fact that we are handling floats and `self.C` is really close to 0. Example:
```python
d1 = 1.0000000000000017 # Some computation errors tend to add digits at the end of the number
d2 = 1.0000000000000017 * 2.05
matrixGroup = System4f(d1, d2) # We use a 4f system because it is a real physical system
# Any matrix with C close but not 0 will do
print(matrixGroup.C) # We check what is the value of the C component of the ewuivalent matrix
```
The output is:
```python
1.1102230246251565e-16
```
Which is **VERY** small, but still not 0. Obviously, a 4f system has no power, but with computational errors, the code considers it has power.
diff --git a/raytracing/tests/testsMatrix.py b/raytracing/tests/testsMatrix.py
index 9c75340..886a9b4 100644
--- a/raytracing/tests/testsMatrix.py
+++ b/raytracing/tests/testsMatrix.py
@@ -344,6 +344,15 @@ class TestMatrix(unittest.TestCase):
         m2 = Matrix(A=1, B=1, C=3, D=4)
         self.assertFalse(m2.isImaging)
 
+    def testHasNoPower(self):
+        f1 = 1.0000000000000017
+        f2 = 2.05 * f1
+
+        # This simulates a 4f system (since we test Matrix, we should only use basic matrices)
+        m = Matrix(1, f1, 0, 1) * Matrix(1, 0, -1 / f1, 1) * Matrix(1, f1, 0, 1) * Matrix(1, f2, 0, 1)
+        m = m * Matrix(1, 0, -1 / f2, 1) * Matrix(1, f1, 0, 1)
+        self.assertFalse(m.hasPower)
+
     def testEffectiveFocalLengthsHasPower(self):
         m = Matrix(1, 2, 3, 4)
         focalLengths = (-1 / 3, -1 / 3)

pip install -e .[dev]
parse_log_pytest
matplotlib numpy
pytest
3.6
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
attrs==22.2.0
certifi==2021.5.30
cycler @ file:///tmp/build/80754af9/cycler_1637851556182/work
importlib-metadata==4.8.3
iniconfig==1.1.1
kiwisolver @ file:///tmp/build/80754af9/kiwisolver_1612282412546/work
matplotlib @ file:///tmp/build/80754af9/matplotlib-suite_1613407855456/work
numpy @ file:///tmp/build/80754af9/numpy_and_numpy_base_1603483703303/work
olefile @ file:///Users/ktietz/demo/mc3/conda-bld/olefile_1629805411829/work
packaging==21.3
Pillow @ file:///tmp/build/80754af9/pillow_1625670622947/work
pluggy==1.0.0
py==1.11.0
pyparsing @ file:///tmp/build/80754af9/pyparsing_1635766073266/work
pytest==7.0.1
python-dateutil @ file:///tmp/build/80754af9/python-dateutil_1626374649649/work
-e git+https://github.com/DCC-Lab/RayTracing.git@ba11e628ea9be0cf8f45efc2013c49529bd2d801#egg=raytracing
six @ file:///tmp/build/80754af9/six_1644875935023/work
tomli==1.2.3
tornado @ file:///tmp/build/80754af9/tornado_1606942266872/work
typing_extensions==4.1.1
zipp==3.6.0

name: RayTracing
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - blas=1.0=openblas
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - cycler=0.11.0=pyhd3eb1b0_0
  - dbus=1.13.18=hb2f20db_0
  - expat=2.6.4=h6a678d5_0
  - fontconfig=2.14.1=h52c9d5c_1
  - freetype=2.12.1=h4a9f257_0
  - giflib=5.2.2=h5eee18b_0
  - glib=2.69.1=h4ff587b_1
  - gst-plugins-base=1.14.1=h6a678d5_1
  - gstreamer=1.14.1=h5eee18b_1
  - icu=58.2=he6710b0_3
  - jpeg=9e=h5eee18b_3
  - kiwisolver=1.3.1=py36h2531618_0
  - lcms2=2.16=hb9589c4_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - lerc=4.0.0=h6a678d5_0
  - libdeflate=1.22=h5eee18b_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgfortran-ng=11.2.0=h00389a5_1
  - libgfortran5=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libopenblas=0.3.21=h043d6bf_0
  - libpng=1.6.39=h5eee18b_0
  - libstdcxx-ng=11.2.0=h1234567_1
  - libtiff=4.5.1=hffd6297_1
  - libuuid=1.41.5=h5eee18b_0
  - libwebp=1.2.4=h11a3e52_1
  - libwebp-base=1.2.4=h5eee18b_1
  - libxcb=1.15=h7f8727e_0
  - libxml2=2.9.14=h74e7548_0
  - lz4-c=1.9.4=h6a678d5_1
  - matplotlib=3.3.4=py36h06a4308_0
  - matplotlib-base=3.3.4=py36h62a2d02_0
  - ncurses=6.4=h6a678d5_0
  - numpy=1.19.2=py36h6163131_0
  - numpy-base=1.19.2=py36h75fe3a5_0
  - olefile=0.46=pyhd3eb1b0_0
  - openssl=1.1.1w=h7f8727e_0
  - pcre=8.45=h295c915_0
  - pillow=8.3.1=py36h5aabda8_0
  - pip=21.2.2=py36h06a4308_0
  - pyparsing=3.0.4=pyhd3eb1b0_0
  - pyqt=5.9.2=py36h05f1152_2
  - python=3.6.13=h12debd9_1
  - python-dateutil=2.8.2=pyhd3eb1b0_0
  - qt=5.9.7=h5867ecd_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sip=4.19.8=py36hf484d3e_0
  - six=1.16.0=pyhd3eb1b0_1
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - tornado=6.1=py36h27cfd23_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - zstd=1.5.6=hc292b87_0
  - pip:
      - attrs==22.2.0
      - importlib-metadata==4.8.3
      - iniconfig==1.1.1
      - packaging==21.3
      - pluggy==1.0.0
      - py==1.11.0
      - pytest==7.0.1
      - tomli==1.2.3
      - typing-extensions==4.1.1
      - zipp==3.6.0
prefix: /opt/conda/envs/RayTracing

raytracing/tests/testsMatrix.py::TestMatrix::testHasNoPower
raytracing/tests/testsMatrix.py::TestMatrix::testApertureDiameter raytracing/tests/testsMatrix.py::TestMatrix::testAxesToDataScale raytracing/tests/testsMatrix.py::TestMatrix::testBackFocalLengthSupposedNone raytracing/tests/testsMatrix.py::TestMatrix::testDisplayHalfHeight raytracing/tests/testsMatrix.py::TestMatrix::testEffectiveFocalLengthsHasPower raytracing/tests/testsMatrix.py::TestMatrix::testEffectiveFocalLengthsNoPower raytracing/tests/testsMatrix.py::TestMatrix::testFiniteBackConjugate raytracing/tests/testsMatrix.py::TestMatrix::testFiniteForwardConjugate raytracing/tests/testsMatrix.py::TestMatrix::testFocusPositions raytracing/tests/testsMatrix.py::TestMatrix::testFocusPositionsNoPower raytracing/tests/testsMatrix.py::TestMatrix::testFrontFocalLengthSupposedNone raytracing/tests/testsMatrix.py::TestMatrix::testInfiniteBackConjugate raytracing/tests/testsMatrix.py::TestMatrix::testInfiniteForwardConjugate raytracing/tests/testsMatrix.py::TestMatrix::testIsImaging raytracing/tests/testsMatrix.py::TestMatrix::testMagnificationImaging raytracing/tests/testsMatrix.py::TestMatrix::testMagnificationNotImaging raytracing/tests/testsMatrix.py::TestMatrix::testMatrix raytracing/tests/testsMatrix.py::TestMatrix::testMatrixBackFocalLength raytracing/tests/testsMatrix.py::TestMatrix::testMatrixExplicit raytracing/tests/testsMatrix.py::TestMatrix::testMatrixFlipOrientation raytracing/tests/testsMatrix.py::TestMatrix::testMatrixFrontFocalLength raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductGaussianBeamMath raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductGaussianBeamWavelengthOut raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductGaussianClippedOverAperture raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductGaussianInitiallyClipped raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductGaussianLength raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductGaussianNotClipped raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductGaussianNotSameRefractionIndex raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductGaussianRefractIndexOut raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductLength raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductMath raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductOutpuRayLength raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductOutputRayAperture raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductRayAlreadyBlocked raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductRayGoesInAperture raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductUnknownRightSide raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductVertices raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductVerticesAllNone raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductVerticesFirstNone raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductVerticesSecondNone raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductVerticesTwoElements raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductVerticesTwoElementsRepresentingGroups raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductWithRayGoesOverAperture raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductWithRayGoesUnderAperture raytracing/tests/testsMatrix.py::TestMatrix::testMatrixProductWithRayMath raytracing/tests/testsMatrix.py::TestMatrix::testPointsOfInterest raytracing/tests/testsMatrix.py::TestMatrix::testPrincipalPlanePositions raytracing/tests/testsMatrix.py::TestMatrix::testPrincipalPlanePositionsNoPower raytracing/tests/testsMatrix.py::TestMatrix::testStrRepresentation raytracing/tests/testsMatrix.py::TestMatrix::testStrRepresentationAfocal raytracing/tests/testsMatrix.py::TestMatrix::testTrace raytracing/tests/testsMatrix.py::TestMatrix::testTraceBlocked raytracing/tests/testsMatrix.py::TestMatrix::testTraceGaussianBeam raytracing/tests/testsMatrix.py::TestMatrix::testTraceMany raytracing/tests/testsMatrix.py::TestMatrix::testTraceManyJustOne raytracing/tests/testsMatrix.py::TestMatrix::testTraceManyThroughInParallel raytracing/tests/testsMatrix.py::TestMatrix::testTraceManyThroughIterable raytracing/tests/testsMatrix.py::TestMatrix::testTraceManyThroughLastRayBlocked raytracing/tests/testsMatrix.py::TestMatrix::testTraceManyThroughNoOutput raytracing/tests/testsMatrix.py::TestMatrix::testTraceManyThroughNotIterable raytracing/tests/testsMatrix.py::TestMatrix::testTraceManyThroughOutput raytracing/tests/testsMatrix.py::TestMatrix::testTraceNullLength raytracing/tests/testsMatrix.py::TestMatrix::testTraceThrough raytracing/tests/testsMatrix.py::TestMatrix::testTransferMatrices raytracing/tests/testsMatrix.py::TestMatrix::testTransferMatrix raytracing/tests/testsMatrix.py::TestMatrix::testWarningsFormat
raytracing/matrix.py
raytracing/matrix.py