SPARKFUN external EEPROM library - issue with arrays

Inf or -Inf requires the max exponent, and the significand must be zero. Otherwise it is NaN (which seems like a waste of bits. Looked it up: turns out there are both quiet and signaling NaNs, and they can contain a payload in the significand bits.)

Due to the biased exponent, that's just one or two bits off

value float as int
1.0 0x3f800000
Inf 0x7f800000
-Inf 0xff800000

You can print the float-as-int

Serial.println(*reinterpret_cast<int32_t*>(&mem_valuefloat), HEX);

How are you showing the value? Serial.print does not print the negative sign unless it's a valid number

size_t Print::printFloat(double number, int digits)
{
  if (digits < 0)
    digits = 2;

  size_t n = 0;

  if (isnan(number)) return print("nan");
  if (isinf(number)) return print("inf");
  if (number > 4294967040.0) return print ("ovf");  // constant determined empirically
  if (number <-4294967040.0) return print ("ovf");  // constant determined empirically

  // Handle negative numbers
  if (number < 0.0)
  {
     n += print('-');
     number = -number;
  }

Also the offset of korr_A[3][4] is 252, which means it ends just before offset 256. (Might be more of a lead if it started there.) What does setMemoryType do?