Product function root extractor

Claim 2

Apparatus for computing the square root of the product of two functions comprising: an energy source; a first variable aperture mask means having an aperture area which is exposed to said energy source and is variable in accordance with the product of two input functions; a second variable aperture mask means having a square aperture area exposed to said energy source; means responsive to the quantity of energy passing through said apertures in said mask means for varying the area of said second variable aperture mask means until it is equal to the area of said first variable aperture mask means, whereby the length of a side of the aperture of said second variable aperture mask means is equal to the square root of the product of said input functions; and means for measuring the length of the side of said aperture and for providing a signal proportional to the square root of the product of said two input functions.

Claim 3

The apparatus of claim 1 wherein said means for varying the area of said second variable aperture mask means includes: means for sensing the quantity of energy passing through said first variable aperture mask means and generating a first signal representative thereof; means for sensing the quantity of energy passing through said second variable aperture mask means and generating a second signal representative thereof; means for comparing said first and second signals to generate an error signal proportional to the difference thereof; and means responsive to said error signal, for changing the aperture area of said second variable aperture mask means, while maintaining its square shape, in a manner tending to null side error signal.

Claim 4

The apparatus of claim 2 wherein said comparing means comprises a bridge comparison circuit and said first and second signal generating means comprise photosensitive detector cells.

Claim 5

The apparatus of claim 2 wherein said second variable aperture mask means includes two overlapping opaque sections forming a square aperture area and said means for changing the area of said second variable aperture mask means while maintaining its square shape includes means for moving said overlapping sections with respect to each other along a diagonal of said square aperture area.

Claim 6

Apparatus for computing the square root of the product of two functions comprising: a first variable aperture light mask means having a first aperture dimension variable in accordance with a first function and a second aperture dimension variable according to a second function; a second variable aperture light mask means having a square aperture shape; a light source exposed to said first and second mask means; means for generating a difference signal representative of the quantitative difference of the light passing through said apertures in each of said variable aperture mask means; and means responsive to said difference signal for varying the aperture area of said second mask means while maintaining its square aperture shape until said difference signal is minimized, thereby equalizing the aperture area of said light mask means and providing a signal proportional to the square root of the product of said functions.

Claim 7

Apparatus for computing the square root of the product of two functions comprising: a first variable aperture light mask means having a first aperture dimension variable in accordance with a first function and a second aperture dimension variable according to a second function; a second variable aperture light mask means having a square aperture shape; a light source exposed to said first and second mask means; means for generating a difference signal representative of the quantitative difference of the light passing through said apertures in each of said variable aperture mask means; and means responsive to said difference signal for varying the aperture area of said second mask means while maintaining its square aperture shape until said difference signal is minimized, thereby equalizing the aperture area of said light mask means and providing a signal proportional to the square root of the product of said functions.

Claim 8

Apparatus as defined in claim 5 for measuring the flow rate and volume of gas in a gas flow line wherein: said first aperture dimension of said first variable aperture light mask means is variable in accordance with the average flow pressure in a gas flow line and said second aperture dimension is variable in accordance with the pressure differential between two spaced points in a gas flow line.

Claim 9

The apparatus of claim 5 wherein said means for generating a difference signal representative of the quantitative difference of light passing through said apertures in each of said variable aperture mask means includes photosensitive detector apparatus connected in a bridge circuit.

Claim 10

The apparatus of claim 5 wherein said second variable aperture light mask means includes two L-shaped opaque members overlapping to form said square aperture shape and said means for varying the aperture are of a said second variable aperture light mask means while maintaining its square aperture shape includes means for moving said overlapping L-shaped members with respect to each other along a diagonal of said square aperture.