How do I perform arithmetic in a makefile?

Question

Is it possible to perform some operations on variables in a makefile? For instance, defining

JPI=4
JPJ=2

Is it possible to define in the sa

Answer 1

In GNU Make with Guile support (i.e. since version 4.0) it is easy to use call to Scheme language for arithmetic or other calculations. It is done without creating any subshell or child process.

An example

JP-I := 4
JP-J := 2
JP-IJ := $(guile (* $(JP-I) $(JP-J) ))

$(info JP-IJ = $(JP-IJ) )
# prints: JP-IJ = 8

See also the manual for Guile Arithmetic Functions.

Possible check for Guile:

ifeq (,$(filter guile,$(.FEATURES)))
  $(error Your Make version $(MAKE_VERSION) is not built with support for Guile)
endif