generate_lut.py

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#!/usr/bin/env python3
 
# Create C/C++ code for two lookup tables.
 
import math
 
# kTableSize and kScaleFactor must match the values in functions.h.
 
# Size of static tables.
kTableSize = 4096
# Scale factor for float arg to int index.
kScaleFactor = 256.0
 
print("// Generated code with lookup tables (see generate_lut.py)")
print('#include "functions.h"')
print("namespace tesseract {")
 
print("const TFloat TanhTable[] = {")
for i in range(kTableSize):
    print("    %a," % math.tanh(i / kScaleFactor))
print("};")
 
print("const TFloat LogisticTable[] = {")
for i in range(kTableSize):
    print("    %a," % (1 / (1 + math.exp(-i / kScaleFactor))))
print("};")
print("} // namespace tesseract.")