def rpMagnitudeError(G, vmini):
z=calcZBpRp(G)<EOL>a = -<NUM_LIT>*power(vmini,<NUM_LIT:3>) + <NUM_LIT>*vmini*vmini - <NUM_LIT>*vmini + <NUM_LIT><EOL>b = -<NUM_LIT>*power(vmini,<NUM_LIT:3>) + <NUM_LIT>*vmini*vmini - <NUM_LIT>*vmini + <NUM_LIT><EOL>c = -<NUM_LIT>*power(vmini,<NUM_LIT:3>) + <NUM_LIT>*vmini*vmini - <NUM_LIT>*vmini - <NUM_LIT><EOL>return <NUM_LIT>*sqrt(power(<NUM_LIT>,a)*z*z+power(<NUM_LIT>,b)*z+power(<NUM_LIT>,c))<EOL>
Calculate the single-field-of-view-transit photometric standard error in the RP band as a function
of G and (V-I). Note: this refers to the integrated flux from the RP spectrophotometer. A margin of 20%
is included.

Parameters
----------

G     - Value(s) of G-band magnitude.
vmini - Value(s) of (V-I) colour.

Returns
-------

The RP band photometric standard error in units of magnitude.