Patent Document ID: 8521392
Application ID: 13191662
Patent Flag: 1

Claim One:
1. A computer program for an internal combustion engine, which causes a computer to execute integral calculation of an integrand for a time point, to thereby calculate a value of a second variable used at each calculation time point, the integrand being defined by: a first variable to which a value is given at all calculation time points; and the second variable to which only an initial value is given, the computer program comprising: processing of reading out, from a storage device, a partial derivative which is obtained by partially differentiating the integrand for the second variable; and at each calculation time point, processing of substituting: one of the initial value and a value of the second variable calculated at a last calculation time point; and a value of the first variable given at a current calculation time point, into the integrand read out from the storage device, to thereby calculate a value of the integrand at the current calculation time point, and then storing the calculation result into the storage device; processing of substituting: one of the initial value and the value of the second variable calculated at the last calculation time point; and the value of the first variable given at the current calculation time point, into the partial derivative read out from the storage device, to thereby calculate a value of the partial derivative at the current calculation time point, and then storing the calculation result into the storage device; processing of storing, into the storage device, an exponential function in which: the calculated value of the integrand at the current calculation time point is used as an initial value; and a value obtained by multiplying the value of the integrand by the value of the partial derivative is used as a gradient; and processing of calculating a value of the second variable used at a next calculation time point, on a basis of the exponential function read out from the storage device, wherein: the processing of calculating a value of the second variable used at a next calculation time point, on a basis of the exponential function read out from the storage device, includes: processing of integrating the exponential function from the current calculation time point to the next calculation time point, and then storing the calculated integral value into the storage device; and processing of adding the integral value read out from the storage device to a value of the second variable at the current calculation time point, to thereby calculate the value of the second variable used at the next calculation time point, and then storing the calculation value into the storage device; the first variable includes variables which represent an opening degree of a throttle valve, an engine speed, and a state of atmosphere; and the second variable is a pressure of an intake pipe.