diff options
Diffstat (limited to 'numpy/lib/financial.py')
| -rw-r--r-- | numpy/lib/financial.py | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/numpy/lib/financial.py b/numpy/lib/financial.py index 503d43647..7f62a81f9 100644 --- a/numpy/lib/financial.py +++ b/numpy/lib/financial.py @@ -180,8 +180,8 @@ def pmt(rate, nper, pv, fv=0, when='end'): 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 + http://www.oasis-open.org/committees/documents.php + ?wg_abbrev=office-formulaOpenDocument-formula-20090508.odt Examples -------- @@ -469,13 +469,22 @@ def rate(nper, pmt, pv, fv, when='end', guess=0.10, tol=1e-6, maxiter=100): Notes ----- - The rate of interest ``rate`` is computed by solving the equation:: + 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 - or, if ``rate = 0``:: + for ``rate``. - fv + pv + pmt * nper = 0 + References + ---------- + 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 """ when = _convert_when(when) |