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FishMarket 1.0
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disk_222
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plplot
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src
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source.zoo
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pldtik.c
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C/C++ Source or Header
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1989-05-15
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2KB
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71 lines
/* If tick == 0, this works out a "nice" interval, so that there */
/* are between 3 and 7.5 major tick intervals in the input range */
/* "vmin" to "vmax". Using this value for the tick interval or */
/* supplied value, it also computes "prec" which specifies */
/* the number of places that should be written after the decimal */
/* point. The recommended number of subticks is returned in */
/* "nsubt" unless the routine is entered with a non-zero value */
/* of "nsubt". The output variable "mode" is set to 0 if */
/* labels are to be written in floating-point format, or to 1 if */
/* they are to be written in fixed-point format. */
#include "plplot.h"
#include <math.h>
void pldtik(vmin, vmax, tick, nsubt, mode, prec)
float vmin, vmax, *tick;
int *nsubt, *mode, *prec;
{
float t1, t2, vmod;
int msd, np, ns;
vmod = max(fabs(vmin),fabs(vmax));
*mode = 0;
if (vmod < 1.0e-2 || vmod > 1.0e6) *mode = 1;
t1 = (float)log10(vmod);
msd = (int)t1;
t1 = (float)log10(fabs(vmax-vmin));
np = (int)t1;
t1 = t1 - np;
if (t1 > 0.7781512503) {
t2 = 2.0 ;
ns = 4;
}
else if (t1 > 0.4771212549) {
t2 = 1.0 ;
ns = 5;
}
else if (t1 > 0.1760912591) {
t2 = 5.0;
ns = 5;
np = np-1;
}
else {
t2 = 2.0;
ns = 4;
np = np-1;
}
if (*tick == 0.0) {
*tick = t2 * pow(10.0,(double)np);
if (vmin > vmax) *tick = -*tick;
if (*nsubt == 0) *nsubt = ns;
if (*mode != 0)
*prec = msd - np;
else
*prec = max(-np,0);
}
else {
t1 = (float)log10(fabs(*tick));
np = (int)t1;
if (*mode != 0)
*prec = msd - np + 1;
else
*prec = max(-np+1,0);
}
}