Fix spelling and warning

Author: WeiqunZhang

Src/FFT/AMReX_FFT.H

@@ -33,7 +33,7 @@ namespace amrex::FFT
  * This class supports Fourier transforms between real and complex data. The
  * name R2C indicates that the forward transform converts real data to
  * complex data, while the backward transform converts complex data to real
- * data. It should be noted that both directions fo transformation are
+ * data. It should be noted that both directions of transformation are
  * supported, not just from real to complex. The scaling follows the FFTW
  * convention, where applying the forward transform followed by the backward
  * transform scales the original data by the size of the input array.

Tests/FFT/R2C/main.cpp

@@ -105,7 +105,7 @@ int main (int argc, char* argv[])
         { // forward and backward
             FFT::R2C<Real,FFT::Direction::both> r2c(geom.Domain());
             r2c.forwardThenBackward(mf, mf2,
-                                    [=] AMREX_GPU_DEVICE (int i, int j, int k, auto& sp)
+                                    [=] AMREX_GPU_DEVICE (int, int, int, auto& sp)
             {
                 sp *= scaling;
             });