Function note

LINEST with no residual degrees of freedom returns zeros and one #NUM!

FUNC.LINEST

FN-LINEST-002: LINEST with no residual degrees of freedom returns zeros and one #NUM!

Quirk · measured · recorded 2026-11-04

With three observations, three x columns and const FALSE, LINEST with stats returns standard errors of 0 and se_y of 0 rather than #DIV/0!, R^2 of 1, F of #NUM!, degrees of freedom 0, ss_resid exactly 0 and ss_reg the sum of y^2.

Call and input routeInputsExcelCorrect valueRecorded in
=INDEX(LINEST({31.78;5.61;-9.09},{53.56,30.22,32;-9,-17.977,47.17;9.4,-11.83,39.39},FALSE,TRUE),2,1)
formula-literal		As typed0
0x0000000000000000		—Excel 16.0.20527.20088 Current Channel, Windows 64-bit (NT 10.0.26200), x86-64, AMD Ryzen 7 4800H, en-ZA
=INDEX(LINEST({31.78;5.61;-9.09},{53.56,30.22,32;-9,-17.977,47.17;9.4,-11.83,39.39},FALSE,TRUE),3,1)
formula-literal		As typed1
0x3ff0000000000000		—Excel 16.0.20527.20088 Current Channel, Windows 64-bit (NT 10.0.26200), x86-64, AMD Ryzen 7 4800H, en-ZA
=INDEX(LINEST({31.78;5.61;-9.09},{53.56,30.22,32;-9,-17.977,47.17;9.4,-11.83,39.39},FALSE,TRUE),4,1)
formula-literal		As typed#NUM!—Excel 16.0.20527.20088 Current Channel, Windows 64-bit (NT 10.0.26200), x86-64, AMD Ryzen 7 4800H, en-ZA
=INDEX(LINEST({31.78;5.61;-9.09},{53.56,30.22,32;-9,-17.977,47.17;9.4,-11.83,39.39},FALSE,TRUE),5,1)
formula-literal		As typed1124.0686
0x409190463f141206		—Excel 16.0.20527.20088 Current Channel, Windows 64-bit (NT 10.0.26200), x86-64, AMD Ryzen 7 4800H, en-ZA

Basis: One fit, 20 selections read through INDEX.

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