surge limiting resistors for full-wave bridge rectifiers
The simplest calculation is to assume the worst:  that at the instant of switch-on the cap on the far side of the bridge is not charged, and therefore presents almost a short circuit at the instant when power is first applied, for that first half-cycle of 50/60Hz, that's the worse case peak current you have to limit, the "inrush current" (to charge up the cap).  Every cycle of the AC after that point, the cap will become more &amp; more charged, drawing less &amp; less current per cycle, until it settles to whatever power is being drawn by the circuit powered.

In that case, the max surge capability for that diode is 30 Amps for 8.3mS (i.e. 1 half-wave of the 60Hz mains frequency).  This is straight off the datasheet.

In that case, R=V/I = 50 / 30 = 1.66 ohms.  Let's say 1.8 or even 2.2 ohms just to be safe, and to choose a standard resistor value (E12-series).

The only problem with this approach is that resistor is always there, dissipating heat (diode is rated for 1.0A continuous, so presumably this is the design max current for the power supply, so Power = IIR = 1.0 * 1.0 * 1.8 = 1.8 Watts, so it won't be a small resistor!  Other real-world solutions would use an NTC resistor whose resistance drops as it heats up, so it limits that inrush current, but then after a few seconds dissipates somewhat less heat (wasted)compared to the 'dumb' resistor.  Or, a relay powered by the power-supply turns on after a short delay that shorts out the resistor.