p = mpfr..pi 200               # 200 bits of precision

x = mpfr..grow(1.0E+0,1000)    # 160 default precision, grown to 1160

y = mpfr..shrink(1.0+0,40)     # 160 default shrunk to 120

z = mpfr..add(p,y)             # inherits 200 bits of precision

a = # 180 bits (not the default 160) because of more digits in the constant

1.00000000000000000000000000000000000000000000000000000E0