# numpy.rate¶

`numpy.``rate`(nper, pmt, pv, fv, when='end', guess=None, tol=None, maxiter=100)[source]

Compute the rate of interest per period.

Deprecated since version 1.18: `rate` is deprecated; for details, see NEP 32 . Use the corresponding function in the numpy-financial library, https://pypi.org/project/numpy-financial.

Parameters
nperarray_like

Number of compounding periods

pmtarray_like

Payment

pvarray_like

Present value

fvarray_like

Future value

when{{‘begin’, 1}, {‘end’, 0}}, {string, int}, optional

When payments are due (‘begin’ (1) or ‘end’ (0))

guessNumber, optional

Starting guess for solving the rate of interest, default 0.1

tolNumber, optional

Required tolerance for the solution, default 1e-6

maxiterint, optional

Maximum iterations in finding the solution

Notes

The rate of interest is computed by iteratively solving the (non-linear) equation:

```fv + pv*(1+rate)**nper + pmt*(1+rate*when)/rate * ((1+rate)**nper - 1) = 0
```

for `rate`.

References

1

NumPy Enhancement Proposal (NEP) 32, https://numpy.org/neps/nep-0032-remove-financial-functions.html

2

Wheeler, D. A., E. Rathke, and R. Weir (Eds.) (2009, May). Open Document Format for Office Applications (OpenDocument)v1.2, Part 2: Recalculated Formula (OpenFormula) Format - Annotated Version, Pre-Draft 12. Organization for the Advancement of Structured Information Standards (OASIS). Billerica, MA, USA. [ODT Document]. Available: http://www.oasis-open.org/committees/documents.php?wg_abbrev=office-formula OpenDocument-formula-20090508.odt

numpy.nper

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