Random number generation with Meta Commands?

Kolbi

Hi all,

I was trying to make a simple random number generator - single digit, -9 to 9 numeric swing and came up with this:

echo floor(10*(cos(sqrt(sensors.analog[0].lastReading * state.upTime))))

Is there a better way to do this?

Cheers,
Kolbi

dc42

What's the use case? We could add a random number function if it would be generally useful.

Kolbi

@dc42 As of now I'm using it to offset prime line and working on making it used to offset prints starting location on the build plate.

Kolbi

Sorry @dc42, use case posted here: https://forum.duet3d.com/topic/17872/automatic-bed-leveling-with-conditional-gcode-iterations/62

Cheers,
Kolbi

Kolbi

Or to make a R2D2 impression...

while iterations <= 4                            ; perform 5 passes
   M300 S{3000+(200*(floor(10*(cos(sqrt(sensors.analog[0].lastReading * state.upTime))))))} P{200+(10*(floor(10*(cos(sqrt(sensors.analog[0].lastReading * state.upTime))))))}
   M300 S{3000+(200*(floor(10*(cos(sqrt(sensors.analog[0].lastReading * state.upTime))))))} P{100+(10*(floor(10*(cos(sqrt(sensors.analog[0].lastReading * state.upTime))))))}
   G4 P200

engikeneer

@dc42 jumping on this one, I would find it quite useful if I could slightly randomise my z home position. I use a piezo nozzle contact to home Z and I have a ziflex magnetic build surface. I find that over time my Z-offset is drifting because repeated probing of the same point is putting an indent in the surface and damaging it.
I'm thinking if I could randomise the probing point within a given area (say a 10mm square) it would give me much less wear on the ziflex and shouldn't impact my z homing accuracy too much (by being in nearly the same place)

mrehorstdmd

I would find it useful for randomly selecting pattern files to run on my sand table.

Kolbi

@dc42, here's the primeline macro - use case:

; 0:/sys/primeline.g
; Print prime-line at a 'randomized' Y positon from -1.1 to -2.9

G1 X0 Z0.6 Y{-2+(0.1*(floor(10*(cos(sqrt(sensors.analog[0].lastReading * state.upTime))))))} F3000.0;
G92 E0.0                                                   ; set E position to 0
G1 Z0.2 X100.0 E30.0 F1000.0                               ; prime line
G92 E0.0                                                   ; set E position to 0
M400                                                       ; finish all current moves / clear the buffer

Cheers,
Kolbi

dc42

I've added a random(nnn) function to the expression evaluator, where n must be a positive integer. It returns a random integer in the range 0 to nnn-1. It will be in the 3.02beta releases.

Kolbi

@dc42 said in Random number generation with Meta Commands?:

It will be in the 3.02beta releases.

Nice! Is there a list of new expected features?

dc42

@Kolbi said in Random number generation with Meta Commands?:

@dc42 said in Random number generation with Meta Commands?:

It will be in the 3.02beta releases.

Nice! Is there a list of new expected features?

You can see what is already implemented or partly implemented at https://github.com/Duet3D/RepRapFirmware/blob/v3-dev/WHATS_NEW_RRF3.md.