scipy.special.

ndtr#

scipy.special.ndtr(x, out=None)#

Cumulative distribution of the standard normal distribution.

Returns the area under the standard Gaussian probability density function, integrated from minus infinity to x

\[\frac{1}{\sqrt{2\pi}} \int_{-\infty}^x \exp(-t^2/2) dt\]

Parameters:

xarray_like, real or complex: Argument
outndarray, optional: Optional output array for the function results

Returns:

scalar or ndarray: The value of the normal CDF evaluated at x

See also

log_ndtr: Logarithm of ndtr
ndtri: Inverse of ndtr, standard normal percentile function
erf: Error function
erfc: 1 - erf
scipy.stats.norm: Normal distribution

Notes

Array API Standard Support

ndtr has experimental support for Python Array API Standard compatible backends in addition to NumPy. Please consider testing these features by setting an environment variable SCIPY_ARRAY_API=1 and providing CuPy, PyTorch, JAX, or Dask arrays as array arguments. The following combinations of backend and device (or other capability) are supported.

Library	CPU	GPU
NumPy	✅	n/a
CuPy	n/a	✅
PyTorch	✅	✅
JAX	✅	✅
Dask	✅	n/a

See Support for the array API standard for more information.

Examples

Evaluate ndtr at one point.

>>> importnumpyasnp
>>> fromscipy.specialimport ndtr
>>> ndtr(0.5)
0.6914624612740131

Evaluate the function at several points by providing a NumPy array or list for x.

>>> ndtr([0, 0.5, 2])
array([0.5 , 0.69146246, 0.97724987])

Plot the function.

>>> importmatplotlib.pyplotasplt
>>> x = np.linspace(-5, 5, 100)
>>> fig, ax = plt.subplots()
>>> ax.plot(x, ndtr(x))
>>> ax.set_title(r"Standard normal cumulative distribution function $\Phi$")
>>> plt.show()

../../_images/scipy-special-ndtr-1.png