\(\text{FileReadReal}\)

You can use the the \(\text{FileReadReal}\) function to read a single single precision or double precision real value.

You can use the \filereadreal backslash command to insert this function.

The following variants of this function are available:

  • \(\text{tuple } \text{FileReadReal} \left ( \text{<file number>} \right )\)

  • \(\text{tuple } \text{FileReadReal} \left ( \text{<file number>}, \text{<size/endian>} \right )\)

The \(\text{<file number>}\) parameter is an integer value returned by one of the \(\text{FileOpen}\ldots\) functions. The \(\text{<size/endian>}\) parameter indicates how the real value to be read is encoded in the file.

If the \(\text{<size/endian>}\) value is not included or is 0, then the \(\text{FileReadReal}\) function assumes that the real is encoded as a string, either with a fixed point representation such as -123.4 or an exponent representation such as -1.234E2. The real value can be positive or negative, including a leading + character and the exponent character E can be upper or lower case. In this mode, the \(\text{FileReadReal}\) function will read up-to but excluding the first non-digit character.

If the \(\text{<size/endian>}\) value is +4 or +8, then the \(\text{FileReadReal}\) function will read the real value in little-endian single or double precision format conforming to IEEE 754-2008. That is, the least significant bit of the mantissa will be at the first (lowest) position in the file.

If the \(\text{<size/endian>}\) value is -4 or -8, then the \(\text{FileReadReal}\) function will real the real value in big-endian single or double precision format conforming to IEEE 754-2008. That is, the sign bit will be at the most significant bit of the byte at the first (lowest) position in the file.

The \(\text{FileReadReal}\) function will return a tuple containing two entries:

  • The real value read from the file.

  • A boolean holding true on success or false on error.

The Figure 136 shows how you can use the \(\text{FileReadReal}\) function.