Political prisoners are so numerous in Iran that the national radio has begun broadcasting visiting hours as a public service, by alphabetical order of inmates' names.

At the same time, the war with Iraq has so intensified Iranian patriotism that wealthy Tehran matrons knit sweaters for Islamic youths at the front and the Army gets some of its provisions from sidewalk collection points where Iranian citizens donate their own high-priced food.

As the Islamic republic lurches toward its third anniversary, Iran seen from the outside remains a revolution in the making, a confusing upheaval in which the nation, having ejected foreign values, is still divided in a blood feud over its own. But the divisions are set aside by most Iranians for the war against Iraq, where U.S.-trained Army officers have collaborated with fanatical Revolutionary Guards in recent weeks to score major and perhaps decisive advances in the 16-month-old conflict.

For most Americans whose close interest in Iran ended when the 52 U.S. hostages were freed a year ago, these developments have become a dim drama unfolding behind a lowered curtain. Apart from covert intelligence and satellite data restricted to the government, daily information about what goes on there is limited to second-hand and frequently partisan accounts broadcast by the government radio or reported by exile opposition groups, several of which are headquartered here.

The French news agency, Agence France-Presse, is the only Western organization allowed to cover Iran regularly, and its dispatches rarely go beyond official pronouncements. Visits by Western correspondents have diminished to almost zero. Journalists for major U.S. publications have been barred altogether. But by comparing exile reports, interviewing diplomats and recent arrivals from Iran, telephoning into the country and monitoring the official radio, it is possible to gain at least a partial idea of life under Islamic rule three years after it began. Several exile groups dispatch envoys back and forth, slipping them from eastern Turkey into Iranian Kurdistan. In addition, their militants here comb through the Tehran press, coloring the results with ideology but discovering facts as well.

What emerges is a picture of ruthless official repression that has succeeded at least for the time being in resisting a challenge by the strongest opposition group, the leftist Mujaheddin-e-Khalq guerrillas. Alongside the internal repression, a compilation of reports shows, significant military victories over Iraq have in the last few months regained much occupied Iranian land, cut Iraqi supply lines and demoralized Iraqi troops. And despite inflation and a long-term economic strain, recent visitors to Iran report the necessities of everyday life are in the marketplace--sometimes at the end of a long line, but available.

The overall impression from a distance, therefore, is that Ayatollah Ruhollah Khomeini's government has improved its immediate hold on power and gained important advantages in the war despite bombings last year and a precarious foreign-exchange situation caused by military expenses and reduced oil production.

In what seems to be a measure of the evolution, Mujaheddin leader Massoud Rajavi has abandoned his earlier pledge to return in triumph within a few months--according to which he would be there now--and has retreated to a prediction that Khomeini will fall sometime in 1982.

As a result of the large-scale bloodletting in recent months, the cadence of Mujaheddin sabotage and assassinations reported by Khomeini's government has slowed noticeably. The attack earlier this week on government buildings at Amol in northern Iran marked the first major operation blamed on Rajavi's Islamic guerrillas in months.

Rajavi, in an interview at his exile headquarters in the Paris suburb of Auvers-sur-Oise, said resistance continues in Iran at a reduced pace but is no longer reported faithfully by government-controlled radio and newspapers.

"There are so many clashes, all over the country," he said.

Iranian diplomats stationed here and Iranian exiles hostile to Rajavi contend instead that Rajavi's group tried to go too fast and, as a result, suffered unbearably high losses to Revolutionary Guards in street battles and executioners in Iran's overflowing prisons.

A wave of assassinations last summer and fall decimated Iran's top Islamic leadership--killing, among others, president Mohammed Ali Rajai, prime minister Mohammed Javad Bahonar and Ayatollah Mohammed Beheshti, head of the ruling Islamic Republican Party. By the government's count, 1,000 clergy were killed.

Then Rajavi's guerrillas, their hopes aroused, attempted what he called a decisive new phase of struggle. At the Mujaheddin leadership's urging, militants took to the streets last fall in an effort to recreate the mass protests that played a crucial role in toppling the shah.

The reaction by Khomeini's shaken government was so brutal, however, that, according to exile accounts, many Mujaheddin sympathizers were killed, jailed or frightened into hiding. By Rajavi's count of government announcements, more than 4,000 Iranians have been executed since June, most identified as Mujaheddin. The real count is twice that, with another 25,000 in jail, Rajavi maintains.

"We disclosed the real face of the man," he said, claiming the bloody campaign turned Iranians against Khomeini for good. "We showed the head of the snake."

Rajavi, who escaped with deposed president Abol Hassan Bani-Sadr in June, is now depicted in the Iranian press as an American agent, holding hands with a grotesque Uncle Sam. When Khomeini returned in triumph to Tehran on Feb. 1, 1979, and launched the Islamic republic, however, Rajavi was among the ayatollah's most effective supporters, with more than 20,000 armed guerrillas and an estimated half million sympathizers.

What happened in the meantime was a confrontation between the Islamic revolution's two basic currents--the anti-Western mullahs who have emerged as masters, and the progressive, often Western-trained idealists who had hoped, in vain it turned out, to marry Islam and modern leftist politics under Khomeini's aegis.

The struggle overshadowed sporadic acts of opposition by monarchist rebels, little heard from except for a spectacular boat hijacking off the coast of Spain by followers of retired general Bahram Aryana. It also coincided with a split in the other main leftist group, the Fedayoun-e-Khalq.

One Fedayoun faction aligned itself in the opposition with Rajavi's Mujaheddin, leftist but strongly Marxist, while the other joined forces with Tudeh, the Moscow-oriented Iranian communist party that has been working in surprising harmony with Khomeini's mullah-based government.

In the official Iranian perspective, the repression grew from popular revulsion at Mujaheddin tactics and repudiation of the vision of Iran espoused by Bani-Sadr and Rajavi. Hossein Mashayakhi, a spokesman for the Iranian Embassy here, said Revolutionary Guards are putting down the Mujaheddin challenge largely because of help from the people, whom Khomeini repeatedly has called on to denounce dissidents even within their own families.

"I can tell you that if the radio announces 20 executions one day and only 10 the next, the people are disappointed," he said. "The more executions there are, the happier they are."

Returning visitors and Iranians here who telephone their families in Tehran report the people also have little reason to be unhappy because of war scarcities. With massive imports and rationing coupons, the government has kept food available. Tehran residents say in the telephone calls that even with coupons they sometimes have to wait in line for gasoline or kerosene, but that essentials have not run out.

In their telephone conversations home, the exiles say, they avoid political talk because the Tehran government taps lines extensively and broke off direct dial service from Paris to make the controls easier.

Inflation, however, has hit hard. Meat that a year ago cost $2 a pound now goes for $6 and rice selling for about 40 cents a pound now costs $2, residents and returning travelers report. Black-market delivery is available for wealthy Tehran families who want to eat more than their ration, but meat obtained through this service costs double the ration coupon price, they say.

Ahmed Salamatian, a member of parliament who fled to exile in France last fall, said recent legislation authorized the central bank to increase the amount of Iranian currency it can print without hard-currency backing. This, he added, demonstrates that the government is straining to meet budget commitments and continue paying for military and other imports.

The bank's governor under Bani-Sadr's administration, Ali Reza Nobari, said in a recent interview in exile that Tehran has only about $650 million in reserves. This was denied by the Islamic government.

Tehran's source of foreign exchange remains oil, despite damage to its refining and pumping facilities. After dropping its prices in line with the Organization of Petroleum Exporting Countries, the National Iranian Oil Co. is exporting about 600,000 barrels a day, according to industry estimates, and a million barrels a day, according to the company.

At the lower estimate, the sales would amount to about $20.5 million a day.

Although this may be low to finance an import-dependent economy simultaneously with a costly war, the Iranian Army has made substantial advances along the 380-mile front with Iraq. Although most of the fighting remains on Iranian soil, the front has moved markedly closer to Iraq's border and crossed inside Iraqi territory in the far north, according to diplomatic sources and eyewitness reports.