plural of prime formula

(mathematics) A formula for calculating the sum of an arithmetical function by means of an inverse Mellin transform.

A formula used in atomic physics to describe the wavelengths of spectral lines of many chemical elements.

plural of structural formula

(logic) A well-formed formula which has not been made by combining simpler well-formed formulas by means of logical connectives.

(chemistry) A structural formula which is reduced (i.e., skeletal) in the sense that carbon atoms forming the backbone of the structure (esp. of an organic compound) are not labeled — they are shown simply as vertices — and hydrogen atoms are not shown at all (except those which are bonded to heteroatoms, or the exceptionally labeled carbon atoms) but heteroatoms are always labeled. (Labels of labeled hydrogen atoms are written next to labels of the atoms that they are bonded to, without a bond drawn between them. If there are several labeled hydrogen atoms bonded to the same atom then they are written as an H with a subscript for their number.) Carbon atoms which are (optionally) labeled tend to be in reactive extremities of the molecule, not the backbone of it.

(organic chemistry) A skeletal formula, especially a schematic representation of benzene as a hexagon made up of alternating single and double lines that represent alternating single and double bonds

plural of distance formula

(logic) A formula which does not have smaller subformulas.

(trigonometry) law of cosines