gcode_macro: Enable use of Python's math module

[iammattcoleman]

Jinja2's native math functionality is fairly limited.

Python's math module includes many functions that are useful for calculations related to 3D printing.

[JamesH1978]

Thankyou for submitting a PR,

Please be aware you need to sign off, as per point 3 in https://github.com/Klipper3d/klipper/blob/master/docs/CONTRIBUTING.md#what-to-expect-in-a-review

Thanks
James

[iammattcoleman]

@JamesH1978 Thanks for pointing that out. I've updated the commit message and rebased the commit on top of master.

[iammattcoleman]

I'm using this in my _START_PRINT macro every time I run a print.

I measured warmup time for my printer's extruder and bed at various temperatures and then plotted the data. I then wrote some G-code that uses the trend line equations to get my printer's extruder and build plate to reach temperature at about the same time. The lines that set stage_two_threshold inside the conditional rely on this code change in order to use math.sqrt():

    {% set bed_temp = params.BED_TEMP|default(60)|float %}
    {% set extruder_temp = params.EXTRUDER_TEMP|default(220)|float %}
    {% set estimated_bed_preheat_time = 0.1607 * bed_temp**2 - 13.904 * bed_temp + 329.03 %}
    {% set estimated_extruder_preheat_time = 0.0022 * extruder_temp**2 + 0.0413 * extruder_temp + 18.567 %}
    {% if estimated_bed_preheat_time > estimated_extruder_preheat_time %}
      {% set first_tool = "heater_bed" %}
      {% set first_tool_target = bed_temp %}
      {% set second_tool = "extruder" %}
      {% set second_tool_target = extruder_temp %}
      {% set preheat_time_difference = estimated_bed_preheat_time - estimated_extruder_preheat_time %}
      {% set square = 160700 * preheat_time_difference - 4544817 %}
      {% set stage_two_threshold = (10 * (math.sqrt(square) + 6952) / 1607) | round(0) %}
    {% else %}
      {% set first_tool = "extruder" %}
      {% set first_tool_target = extruder_temp %}
      {% set second_tool = "heater_bed" %}
      {% set second_tool_target = bed_temp %}
      {% set preheat_time_difference = estimated_extruder_preheat_time - estimated_bed_preheat_time %}
      {% set square = 880000 * preheat_time_difference - 16168391 %}
      {% set stage_two_threshold = ((math.sqrt(square) - 413) / 44) | round(0) %}
    {% endif %}
    #RESPOND MSG="Estimated times: bed = {estimated_bed_preheat_time|round(1)}, extruder = {estimated_extruder_preheat_time|round(1)}. Begin heating {second_tool} when {first_tool} reaches {stage_two_threshold}°C."
    # Start heating the first tool.
    SET_HEATER_TEMPERATURE HEATER={first_tool} TARGET={first_tool_target}
    # Reset the Z offset.
    SET_GCODE_OFFSET Z=0.0
    # Home the printer.
    G28
    # Start heating the second tool after the first tool has reached the stage two threshold temperature.
    TEMPERATURE_WAIT SENSOR={first_tool} MINIMUM={stage_two_threshold}
    SET_HEATER_TEMPERATURE HEATER={second_tool} TARGET={second_tool_target}
    # Wait for the tools to reach temperature.
    TEMPERATURE_WAIT SENSOR={first_tool} MINIMUM={first_tool_target}
    TEMPERATURE_WAIT SENSOR={second_tool} MINIMUM={second_tool_target}