In the dark times before operational amplifiers were really a thing, power supplies often were single supply type where zero voltage rail was earthed or "common".
When operational amplifiers became widely available and affortable, this type of splitter was by far most inexpensive and easiest way to supply both positive and negative voltage with common center tap or zero voltage line. Note that your power supply and this device must be "floating". Don't ground the negative supply!
In this setup, input voltage is limited to 30V by LM741 opamp maximum voltage rating. So, 15-0-15 or ±15 volts is the upper limit. Practical low end is limited to six volt supply, ie. 3-0-3 or ±3 volts minimum. With 2N3055 power transistor 10 watts of power is possible with good heat sink. And that is calculated from half of supply voltage: If ±10 volts is required (20 volt input) with 1A current then that will be 10 watts.