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/* $Id$ */
/*.......1.........2.........3.........4.........5.........6.........7.........8
================================================================================
FILE d_dt/cfunc.mod
Copyright 1991
Georgia Tech Research Corporation, Atlanta, Ga. 30332
All Rights Reserved
PROJECT A-8503-405
AUTHORS
6 June 1991 Jeffrey P. Murray
MODIFICATIONS
30 Sept 1991 Jeffrey P. Murray
SUMMARY
This file contains the functional description of the d_dt
(differentiator) code model.
INTERFACES
FILE ROUTINE CALLED
CMutil.c void cm_smooth_corner();
CM.c void *cm_analog_alloc()
void *cm_analog_get_ptr()
int cm_analog_integrate()
REFERENCED FILES
Inputs from and outputs to ARGS structure.
NON-STANDARD FEATURES
NONE
===============================================================================*/
/*=== INCLUDE FILES ====================*/
/*=== CONSTANTS ========================*/
/*=== MACROS ===========================*/
/*=== LOCAL VARIABLES & TYPEDEFS =======*/
/*=== FUNCTION PROTOTYPE DEFINITIONS ===*/
/*==============================================================================
FUNCTION cm_d_dt()
AUTHORS
6 Jun 1991 Jeffrey P. Murray
MODIFICATIONS
30 Sep 1991 Jeffrey P. Murray
SUMMARY
This function implements the d_dt code model.
INTERFACES
FILE ROUTINE CALLED
CMutil.c void cm_smooth_corner();
CM.c void *cm_analog_alloc()
void *cm_analog_get_ptr()
int cm_analog_integrate()
RETURNED VALUE
Returns inputs and outputs via ARGS structure.
GLOBAL VARIABLES
NONE
NON-STANDARD FEATURES
NONE
==============================================================================*/
/*=== CM_D_DT ROUTINE ===*/
void cm_d_dt(ARGS)
{
double *in, /* current input value */
*in_old, /* previous input value */
out, /* output */
dum, /* fake input value...used for truncation
error checking */
gain, /* gain parameter */
out_offset, /* output offset parameter */
out_lower_limit, /* output mower limit */
out_upper_limit, /* output upper limit */
limit_range, /* range of output below out_upper_limit
or above out_lower_limit to which
smoothing will be applied */
pout_pin, /* partial derivative of output
w.r.t. input */
dumpout_pin, /* fake partial derivative of output
w.r.t. input (for use with integration */
delta, /* delta time value = TIME - T(1) */
pout_gain; /* temporary storage for partial
returned by smoothing function
(subsequently multiplied w/pout_pin) */
Mif_Complex_t ac_gain; /* AC gain */
/** Retrieve frequently used parameters (used by all analyses)... **/
gain = PARAM(gain);
if (ANALYSIS != MIF_AC) { /**** DC & Transient Analyses ****/
/** Retrieve frequently used parameters... **/
out_offset = PARAM(out_offset);
out_lower_limit = PARAM(out_lower_limit);
out_upper_limit = PARAM(out_upper_limit);
limit_range = PARAM(limit_range);
/** Test for INIT; if so, allocate storage, otherwise, retrieve
previous timepoint input value... **/
if (INIT==1) { /* First pass...allocate storage for previous state. */
/* Also, calculate roughly where the current output */
/* will be and use this value to define current state. */
cm_analog_alloc(TRUE,sizeof(double));
}
/* retrieve previous values */
in = cm_analog_get_ptr(TRUE,0); /* Set out pointer to current
time storage */
in_old = cm_analog_get_ptr(TRUE,1); /* Set old-output-state pointer
to previous time storage */
if ( 0.0 == TIME ) { /*** Test to see if this is the first ***/
/*** timepoint calculation...if ***/
*in_old = *in = INPUT(in); /*** so, return a zero d/dt value. ***/
out = 0.0; /*** so, return a zero d/dt value. ***/
pout_pin = 0.0;
}
else { /*** Calculate value of d_dt.... ***/
delta = TIME - T(1);
*in = INPUT(in);
out = gain * (*in - *in_old) / delta + out_offset;
pout_pin = gain / delta;
}
/*** Smooth output if it is within limit_range of
out_lower_limit or out_upper_limit. ***/
if (out < (out_lower_limit - limit_range)) { /* At lower limit. */
out = out_lower_limit;
pout_pin = 0.0;
}
else {
if (out < (out_lower_limit + limit_range)) { /* Lower smoothing range */
cm_smooth_corner(out,out_lower_limit,out_lower_limit,limit_range,
0.0,1.0,&out,&pout_gain);
pout_pin = pout_pin * pout_gain;
}
else {
if (out > (out_upper_limit + limit_range)) { /* At upper limit */
out = out_upper_limit;
pout_pin = 0.0;
}
else {
if (out > (out_upper_limit - limit_range)) { /* Upper smoothing region */
cm_smooth_corner(out,out_upper_limit,out_upper_limit,limit_range,
1.0,0.0,&out,&pout_gain);
pout_pin = pout_pin * pout_gain;
}
}
}
}
/** Output values for DC & Transient **/
OUTPUT(out) = out;
PARTIAL(out,in) = pout_pin;
/* this cm_analog_integrate call is required in order to force
truncation error to be evaluated */
cm_analog_integrate(out,&dum,&dumpout_pin);
}
else { /**** AC Analysis...output (0.0,s*gain) ****/
ac_gain.real = 0.0;
ac_gain.imag= gain * RAD_FREQ;
AC_GAIN(out,in) = ac_gain;
}
}