Compareison of two numbers in Pbasic

Cogburn

I want to compare two values returned from RCTime for two photoresistors.. If these values are within 10 % of each other, I want the stamp to execute a loop to read RCTime again. If the value collected from the left photoresistor is 10% or more higher than the value collected for the right photoresistor, I want a stepper motor to move to the left by a small increment. If the value for the right photoresistor is more than 10% higher than the left one, I want the stepper motor to move to the right by a small increment. I have the stepper moving left and right at my command. I have the photoresistors reading values that I can compare but I can't figure out how to let Pbasic make the comparison. Any ideas?

SRLM

Look at the "if" command...

Tracy Allen

For example,

DO
' get RCTIME values here, then...
  IF RCTL >= RCTR + (RCTR / 10) THEN
     GOSUB move_Left
  ELSEIF RCTR >= RCTL + (RCTL/10) THEN
    GOSUB move_Right
  ENDIF
LOOP

There are other ways to skin the cat, for example the 10% rule can be done with this formula
IF RCTL >= RCTR */ 282 THEN ' means, RCTL 10% larger than RCTR, look up the */ operator

Here is another way using the SELECT:CASE command and the */282 for 110% and */230 for 90%:

DO
  ' get RCTIME values here, then...
  SELECT RCTL
    CASE >= RCTR */ 282
      GOSUB move_Right
    CASE <= RCTR */ 230
      GOSUB move_Left
    ENDSELECT
LOOP

Or, another way using the LOOKDOWN command. For this one you have to create a dummy subroutine "do_nothing" that just RETURNs.

ix VAR Nib
DO
  ' get RCTIME values here, then...
  LOOKDOWN RCTL, <=[noparse][[/noparse]RCTR */ 240, RCTR*/282, 65535], ix  ' RCTL is <90% or >110% or in between, ix=0,1 or 2
  ON ix  GOSUB move_Right, do_nothing, move_Left
LOOP

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Tracy Allen
www.emesystems.com