单词 | initial values |
释义 | > as lemmasinitial values d. Mathematics. initial condition, each of a set of conditions giving the values ( initial values) of dependent variables or their derivatives for a single set of values of the independent variables. ΘΚΠ the world > relative properties > number > calculus > [noun] > differential calculus > differential equations > conditions > values initial values1834 boundary value1898 the world > relative properties > number > calculus > [noun] > differential calculus > differential equations > conditions boundary condition1902 initial condition1902 1834 W. Hamilton in Philos. Trans. (Royal Soc.) 124 250 No general solution has been obtained assigning (as a complete solution ought to do) 3n relations between the n masses.., the 3n varying coordinates.., the varying time t, and the 6n initial data of the problem, namely, the initial coordinates.., and their initial rates of increase..; the quantities called here initial being those which correspond to the arbitrary origin of time.] 1834 W. Hamilton in Philos. Trans. (Royal Soc.) 124 273 The problem of integrating these [differential] equations consists in proposing to assign, by their means, six relations between the time t, the masses m1m2, the six varying coordinates..and their initial values and initial rates of increase. 1890 A. R. Forsyth Theory Differential Equations I. iii. 82 He [sc. Jacobi] shewed that the introduction of ‘initial values’ of the variables..renders it possible to take the integrals of the first subsidiary system in a form, which leads immediately to the transformation of the equation. 1902 A. R. Forsyth Theory Differential Equations IV. i. 4 The conditions, as to the arbitrarily assigned values to be acquired at ζ by w and its derivatives, are called the initial conditions; the values are called the initial values. 1920 H. T. H. Piaggio Elem. Treat. Differential Equations iv. 53 As t usually denotes time and x and y rectangular coordinates, a condition such as z = 0 when t = 0 is called an initial condition, while one such as z = 0 if x = 0, or if x = l, or if y = x, is called a boundary condition. 1957 L. Fox Numerical Solution Two-point Boundary Probl. i. 5 Boundary-value problems can always be solved in theory, and often in practice, by a combination of initial-value problems, the extra initial conditions being chosen more or less arbitrarily but finally adjusted to satisfy the prescribed boundary conditions. 1968 L. Fox & D. F. Mayers Computing Methods for Scientists & Engineers iii. 30 We need two conditions, and here there are two main possibilities. In the first, giving the so-called initial-value problem, we are provided with two adjacent values ys and ys + 1 for some s, or possibly ys and some linear combination of ys − 1, ys, and ys + 1... The second possibility, giving the so-called boundary-value problem, is the specification say of y0 and yn, the values at the two ends of some range. < as lemmas |
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