onlineregression14:   Multiple nonlinear regression   ⇒   y = f(x1, x2) Formulas u = log(x1)           v = log(x2)           w = log(y) t1 = n∑wv - ∑w∑v           t2 = n∑u∑v - ∑u∑v          t3 = n∑v2 - (∑v)2 t4 = n∑wu - ∑w∑u           t5 = n∑uv - ∑u∑v           t6 = n∑u2 - (∑u)2 t7 = n∑v2 - (∑v)2 β1 = (t1*t2 - t3*t4)/(t5*t5 - t6*t7)          β2 = (t4 - β1*t6)/t2 α = (∑w - β1∑u - β2∑v)/n          a = 10[(∑w - β1∑u - β2∑v)/n] b1 = β1          b2 = β2          y = a x1b1 x2b2 Reference Ponce, V. M. 1989. Engineering Hydrology, Principles and Practices. Prentice Hall, page 241-243. Example INPUT DATA: Enter array size n:      Enter corresponding values of arrays y, x1 and x2 (separate each value with a comma; maximum string length is 300 characters). y:      x1:      x2:      ECHO OF INPUT: n =   y(1) =  .    x1(1) =  .    x2(1) =  .    OUTPUT: a =            b1 =            b2 =                      y = x1 x2   Your request was processed at  06:02:54 pm on August 28th, 2008   [ 080828  18:02:54 ]. Thank you for running onlineregression13.   Please call again.   [070419]

 

online calc
normal depth	critical depth	discharge in culvert	critical slope	sequent depth HJ	energy loss HJ
discharge sluice	discharge weir	discharge channel	initial sequent HJ	critical constriction	efficiency HJ
M1 wsprofile	M2 wsprofile	M3 wsprofile	S1 wsprofile	S2 wsprofile	S3 wsprofile
C1 wsprofile	H2 wsprofile	A2 wsprofile	C3 wsprofile	H3 wsprofile	A3 wsprofile
tractive force				ogee spillway	Hazen-Williams
creager	rational	slope-area	linear reservoir	storage indication 1	storage indication 2
Muskingum	Muskingum-Cunge	time-area	Clark UH	cascade of linear reservoirs
Blaney-Criddle	Penman	Penman-Monteith	Thornthwaite	Priestley-Taylor
Gumbel	Gumbel 2	Log Pearson	Log Pearson 2	TR-55 graphical	convolution
S-hydrograph	curve number	time of concentration
hyperbolic regression		one-predictor linear	one-predictor nonlinear	two-predictor linear	two-predictor nonlinear
USLE	Dendy-Bolton	Shields	Duboys	Colby	reservoir design life