i have an issue with the precision of the conversion.
There is no way to perfectly represent 0.1 in binary floating point (without infinite bits). This conversion is as accurate as it can be within the size of the floating point number type (double or float).
x values in my problem will not be much different that 0.1, or 0.01 (it is a STEP value for a plot function).
Is there a special Qt function to chop off the last 5-6 digits?
For display purposes you can format the number, rounded at a certain number digits to the right of the of decimal point, using QString::number() using the 'e', 'E', or 'F' formats (or the QLocale equivalent).