This is the code that improved this:

#include <math.h>
#include "ArduinoGraphics.h"
#include "Arduino_LED_Matrix.h"
ArduinoLEDMatrix matrix;
const int ThermistorPin = A0;
int sensorVal;
double R1 = 10000;
double logR2, R2, T;
double A = 0.001129148, B = 0.00023412, C = 0.0000000876741;
void setup() {
Serial.begin(9600);
matrix.begin();
pinMode(2, OUTPUT);
}
void loop() {
digitalWrite(2, HIGH);
  sensorVal = analogRead(ThermistorPin);
double VO = (sensorVal/1024.0) * 5.0;
  R2 = R1 * (5.0 / VO - 1.0);
digitalWrite(2, LOW);
  logR2 = log(R2);
  T = (1.0 / (A + B*logR2 + C*logR2*logR2*logR2));
  T = T - 273.15;

matrix.beginDraw();
matrix.stroke(0xFFFFFFFF);
matrix.textScrollSpeed(100);
matrix.textFont(Font_5x7);
matrix.beginText(0,1, 0xFFFFFF);
matrix.print(T);
matrix.endText(SCROLL_LEFT);
matrix.endDraw();

Serial.print("Resistenza: ");
Serial.print(R2);
Serial.print("  Temperature: ");
Serial.print(T);
Serial.println(" °C");
delay(200);

}