/usr/include/freefoam/foamCalcFunctions/ is in libfreefoam-dev 0.1.0+dfsg+1-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/freefoam/foamCalcFunctions/addSubtract.H
/usr/include/freefoam/foamCalcFunctions/calcType.H
/usr/include/freefoam/foamCalcFunctions/components.H
/usr/include/freefoam/foamCalcFunctions/div.H
/usr/include/freefoam/foamCalcFunctions/interpolate.H
/usr/include/freefoam/foamCalcFunctions/mag.H
/usr/include/freefoam/foamCalcFunctions/magGrad.H
/usr/include/freefoam/foamCalcFunctions/magSqr.H
/usr/include/freefoam/foamCalcFunctions/randomise.H
/usr/include/freefoam/foamCalcFunctions/writeAddSubtractField.C
/usr/include/freefoam/foamCalcFunctions/writeAddSubtractValue.C
/usr/include/freefoam/foamCalcFunctions/writeComponentFields.C
/usr/include/freefoam/foamCalcFunctions/writeDivField.C
/usr/include/freefoam/foamCalcFunctions/writeInterpolateField.C
/usr/include/freefoam/foamCalcFunctions/writeMagField.C
/usr/include/freefoam/foamCalcFunctions/writeMagGradField.C
/usr/include/freefoam/foamCalcFunctions/writeMagSqrField.C
/usr/include/freefoam/foamCalcFunctions/writeRandomField.C