Simple fma (usually "fused multiply-add", but in this case it's not really fused so we'll say "fixed", or "functional", or "fun", or the recursive backronym "fma is not unix") template helper for Django — multiply the first two numbers provided and then add the last to that. Optional p= kwarg for rounding results to a fixed precision. When used …

gistfile1.txt

from django import template
#import helper_from_linked_gist as template
register = template.Library()

@register.simple_tag              # {% fma m x b %}
#@register.assignment_tag         # {% fma m x b as y %}
#@register.simple_assignment_tag  # optional "as y", requires using helper_from_linked_gist above
def fma(x, y, z, p=None):
    v = float(x) * float(y) + float(z)
    return v if p is None else ("%%.%uf" % p) % v