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Equation 3 · Part 6 · How Scientific Instruments and Metrology Actually Work

=

y=f(x1,x2,…,xN)y = f(x_1, x_2, \ldots, x_N)
=

What this part means

The expressions on both sides represent the same quantity under the stated assumptions.

Its job in the formula

The equals sign connects the complete expression on the left with the complete expression on the right. Both sides must have compatible units.

The passage around this formula

The GUM’s central move is to treat every measured or estimated quantity a result depends on as a random variable with its own estimated standard uncertainty, and then to propagate those uncertainties through the mathematical relationship that produces the final result. If a measurement result y is a function of N input quantities, y = f(x1x_1, x2x_2, …\ldots, xNx_N) , the combined standard uncertainty is obtained from a first-order Taylor expansion of that function:

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Learn the underlying idea

An equals sign says that the expression on its left and the expression on its right have the same value under the stated definitions and assumptions.

Open the illustrated equality: what the equals sign claims guide →

Sources cited in the article section

These citations provide research context; check each source for the exact claim it supports.