Dear Mem:
Here is the final code, for the sketch:
#include <LiquidCrystal.h>
//create object to control an GMD1602K LCD.
LiquidCrystal lcd(12, 11, 2, 7, 8, 9, 10);
void setup(){
// don't need pinmode for analog inputs
}
void loop() {
float val; // no nead to initialize, the values are set in the first lines of code
static float acum; // states acum as cummulative
float x; // aux variable for calling subroutine void
val = analogRead(1); // read pot value
val = val/3.3; // generate decimals
acum = acum +val; // Defines acum as sum of pot values
lcd.clear(); // Cleans display
/* Prints pot value and title in first line */
lcd.setCursor(0, 0);
lcd.print("Pot=");
lcd.setCursor(6,0); // 6 is the column (starting from 0), 0 is the line starting from 0
x = val; // assigns val to x before calling void
lcdPrintFloat(x,1); // print val to one decimal place
delay (500);
/* Prints accumulated pot values and title in second line */
lcd.setCursor(0,1); // set LCD to print acum on line=2, pos=0.
lcd.print("Acum= ");
lcd.setCursor(6,1);
x = acum; // assigns acum to x, before calling void
lcdPrintFloat(x,2); // should print sum of pot values
digitalWrite(13, LOW); // blinks yellow led for delay seconds
delay (2000);
digitalWrite(13, HIGH);
if( x <= 0)
while(true); // stop displaying values if val goes negative
}
void lcdPrintFloat( float x, byte precision){
// prints val on a ver 0012 text lcd with number of decimal places determine by precision
// precision is a number from 0 to 6 indicating the desired decimal places
if(x < 0.0){
lcd.print('-');
x = -x;
}
lcd.print ((long)x); //prints the integer part
if( precision > 0) {
lcd.print("."); //prints decimal point
unsigned long frac;
unsigned long mult = 1;
byte padding = precision -1;
while(precision--)
mult *=10; //"amplifies" decimal values
if(x >= 0)
frac = (x - int(x)) * mult;
else
frac = (int(x)- x) * mult;
unsigned long frac1 = frac;
while( frac1 /= 10 )
padding--; // ¿?
while( padding--)
lcd.print("0");
lcd.print(frac,DEC) ;
}
}
I made a few comment changes, and made the function void on an aux variable "x" to make it more general to be called several times. 
Thank you very much for your valuable help.
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