[mlir] fix latex formulas in the tutorial

Author: ftynse

mlir/docs/Tutorials/transform/ChH.md

@@ -583,10 +583,11 @@ LLVM IR and processed by the LLVM compiler to produce an executable or JITted.
 
 The generated code runs in ~420ms on an Intel processor with Skylake
 microarchitecture clocked at 2.0GHz. Given that the computation performs
-$5*80*100*128*(2*3*3*128 + 2) ~= 5.9 * 10^9$ floating point operations, it
-reaches ~14 GFlops. With 1 FMA unit available, the single-core performance of
-the test processor is 64 GFlops $16 * 2 * 2 * 10^9$, where 16 is the vector
-width), so only 22% of the theoretical peak is achieved.
+$`5 \cdot 80 \cdot 100 \cdot 128 \cdot (2 \cdot 3 \cdot 3 \cdot 128 + 2) \approx 5.9 * 10^9`$
+floating point operations, it reaches ~14 GFlops. With 1 FMA unit available,
+the single-core performance of the test processor is 64 GFlops
+($`16 \cdot 2 \cdot 2 \cdot 10^9`$, where 16 is the vector width), so only 
+22% of the theoretical peak is achieved.
 
 The code produced by Halide runs in ~120ms on the same processor, a 3.5x
 improvement and 77% of peak. Let us analyze the generated assembly to understand