# map(ChainComplex,ChainComplex,Function) -- make a map of chain complexes

## Synopsis

• Function: map
• Usage:
map(C,D,f) or map(C,D,f,Degree=>d)
• Inputs:
• C,
• D,
• f, , a function such that f(i) is a matrix D_i --> C_(i+d)
• Optional inputs:
• Degree => ..., default value null, specify the degree of a map
• DegreeLift => ..., default value null, make a ring map
• DegreeMap => ..., default value null, make a ring map
• Outputs:
• , a map of chain complexes D --> C

## Description

If the degree d is not given, then d=0 is assumed.

The function f is called only for those indices that represent spots occupied in both the source and target chain complexes.

## Caveat

This function does not check that the maps f(i) commute with the differential of the chain complexes.