/*  sdcexp1.cpp  by K.Tsuru  */
// function ID 3521   DRADIX, constant
/*************************
base of natural logarithm exp(1).
In header "snmath.h" the function prototype is given below
--------
SDouble E(const SDouble* e = NULL, SDouble (*pfCalcFunc)() = SNE);
--------
Remade at version 2.30.
**************************/
#ifndef SN_H
#include "sn.h"
#endif
static SDouble* exp1 = NULL;    //keep in the static memory
static uint exp1Size = 0;

uint ESize() { return exp1Size; }

void EFree(){   //free the momory of exp1
    if(exp1Size == 0) return;
    delete exp1;    exp1 = NULL;        exp1Size = 0;
}
SDouble E(const SDouble* userE, SDouble (*pfCalcFunc)()){
    if(exp1 == NULL) exp1 = new SDouble;
    uint curMaxSize = exp1->MaxSize(); // current max size
    if( exp1Size < curMaxSize ){
#if UsesSNConstantFile
        if(userE == NULL){  //called by default argument
            int enough;
/**********************************************************************************
UpdateConstantFile() recursively calls this function E() via SetConstByFile()
of which userE != NULL, then does not come here and processing below has been
done.
**********************************************************************************/
            enough = UpdateConstantFile(E_FILE, E, pfCalcFunc, curMaxSize);
            if(enough != NO_SNC_FILE) return *exp1;
        }
#endif
        exp1->ShowMessage("Evaluating E() now.....");
        EntryConst(userE, exp1, pfCalcFunc,  &exp1Size);
        exp1->ShowMessage(" Finished.\n"); // ver. 2.17

        exp1Size = curMaxSize;
    }
    return *exp1;
}